Detailed Instructions: You are given a paragraph, a question and some answer options (associated with "A", "B", "C", "D", etc.) You need to list all the correct answer options with their associated letters (e.g. "A" can be a valid answer). Note that sometimes, more than one option can answer the question correctly and completely. In those cases, please generate all such options separated by a comma (e.g. "A, B" is a valid answer). Do not generate anything else apart from one or more of the following characters: 'A', 'B, 'C', 'D', etc.
Problem:Paragraph- Sent 1: An archaeological party explore some caverns underground .
Sent 2: Dr. Campbell and Dr. Hughes are the two leaders of the archaeological expedition , and get separated .
Sent 3: While Dr. Hughes finds an alien corpse with a fossilized diamond , Dr. Campbell finds hieroglyphics at the cost of the party except for Hughes and himself .
Sent 4: Two years later , Campbell and his assistant Holly are digging up the bones of Yonggary , a gargantuan dinosaur 50 times the size of a tyrannosaurus rex .
Sent 5: Out of nowhere , people slowly are being killed around the site .
Sent 6: While Holly is working Dr. Hughes , who has been legally dead for 2 years , goes to Holly and tells her to stop the dig .
Sent 7: Dr. Campbell comes into the tent and sends Dr. Hughes off .
Sent 8: Holly quits the expedition when another `` Accident '' occurs .
Sent 9: In the town bar , Dr. Hughes finds Holly and takes her back to her Hotel room to tell her why he thinks the bones of the Dinosaur , Which he calls Yonggary , are going to bring the end of the world .
Sent 10: After explaining , Holly and Hughes go to the site to stop Campbell but it is too late and Aliens resurrect Yonggary .
Sent 11: After Yonggary's first appearance , the Army comes in and takes Holly and Campbell to an army base when Yonggary is dispatched by the aliens again .
Sent 12: The army sends choppers after Yonggary , but he destroys them .
Sent 13: Yonggary is then sent to the city and does some damage , where some jets attack him .
Sent 14: Then Yonggary is transported to a power plant where he is attacked by rocket pack soldiers .
Sent 15: During the fight , Hughes and Holly find out that the diamond on Yonggary's forehead is the device giving the aliens control of Yonggary . 
Question: What was the "accident" that caused Holly to quit the expedition? (A) People are killed (B) Someone was killed (C) Finding bones.
Solution:
A, B.