Given a text passage, you need to generate a suitable title as the output. The output title should be one of the words/phrases used in the passage and must be no longer than five words. 
One example: Paragraph:  Concept work for Valkyria Chronicles III began after development finished on Valkyria Chronicles II in early 2010 , with full development beginning shortly after this . The director of Valkyria Chronicles II , Takeshi Ozawa , returned to that role for Valkyria Chronicles III . Development work took approximately one year . After the release of Valkyria Chronicles II , the staff took a look at both the popular response for the game and what they wanted to do next for the series . Like its predecessor , Valkyria Chronicles III was developed for PlayStation Portable : this was due to the team wanting to refine the mechanics created for Valkyria Chronicles II , and they had not come up with the " revolutionary " idea that would warrant a new entry for the PlayStation 3 . Speaking in an interview , it was stated that the development team considered Valkyria Chronicles III to be the series ' first true sequel : while Valkyria Chronicles II had required a large amount of trial and error during development due to the platform move , the third game gave them a chance to improve upon the best parts of Valkyria Chronicles II due to being on the same platform . In addition to Sega staff from the previous games , development work was also handled by Media.Vision. The original scenario was written Kazuki Yamanobe , while the script was written by Hiroyuki Fujii , Koichi Majima , Kishiko Miyagi , Seiki Nagakawa and Takayuki Shouji . Its story was darker and more somber than that of its predecessor . 
 The majority of material created for previous games , such as the BLiTZ system and the design of maps , was carried over . Alongside this , improvements were made to the game 's graphics and some elements were expanded , such as map layouts , mission structure , and the number of playable units per mission . A part of this upgrade involved creating unique polygon models for each character 's body . In order to achieve this , the cooperative elements incorporated into the second game were removed , as they took up a large portion of memory space needed for the improvements . They also adjusted the difficulty settings and ease of play so they could appeal to new players while retaining the essential components of the series ' gameplay . The newer systems were decided upon early in development . The character designs were done by Raita Honjou , who had worked on the previous Valkyria Chronicles games . When creating the Nameless Squad , Honjou was faced with the same problem he had had during the first game : the military uniforms essentially destroyed character individuality , despite him needing to create unique characters the player could identify while maintaining a sense of reality within the Valkyria Chronicles world . The main color of the Nameless was black . As with the previous Valkyria games , Valkyria Chronicles III used the CANVAS graphics engine . The anime opening was produced by Production I.G.   Question: what is the suitable title of the passage ?
Solution is here:  Valkyria Chronicles
Explanation:  It is clear from the passage that the answer is Valkyaria Chronicles, as it appears most frequently in the passage.

Now, solve this: Paragraph:    The plain maskray generally hunts at the surface of the bottom substrate , rather than digging for prey . Its diet consists predominantly of caridean shrimp and polychaete worms . Small bony fishes are also eaten , along with the occasional penaeid prawn or amphipod . Larger rays consume a greater variety of prey and relatively more polychaete worms when compared to smaller rays . This species is parasitized by the tapeworm Acanthobothrium jonesi . 
 Like other stingrays , the plain maskray is viviparous with the developing embryos sustained to term by histotroph ( " uterine milk " ) produced by the mother . Mature females have a single functional ovary and uterus , on the left . Litter size is one or two ; the newborns measure 12 – 14 cm ( 4 @.@ 7 – 5 @.@ 5 in ) across . Males and females reach sexual maturity at disc widths of 20 – 21 cm ( 7 @.@ 9 – 8 @.@ 3 in ) and 18 – 19 cm ( 7 @.@ 1 – 7 @.@ 5 in ) respectively . The maximum lifespan is estimated to be 9 years for males and 13 years for females .   Question: what is the suitable title of the passage ?
Solution:
 Biology and ecology