You are given a science question (hard-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

Until recently, only a small part of the human DNA was known to have a specific function. The rest of the DNA was thought to be unimportant. New evidence now suggests that all DNA is needed in certain gene functions. Which statement best describes the significance of this new evidence?  
 (A) It will make the study of DNA much simpler. (B) It proves that DNA is less important than originally thought. (C) It provides evidence that scientific results should not be challenged. (D) It demonstrates that scientific knowledge is subject to change.
D

Which phrase does not describe asexual reproduction in organisms?  
 (A) requires two parents (B) little variation in offspring (C) only one type of cell involved (D) duplicates its genetic material
A

In the process of photosynthesis, green plants use energy from sunlight to make which product?  
 (A) carbon dioxide (B) chlorophyll (C) sugar (D) DNA

C

