instruction:
In this task, you need to answer basic science questions. For each question, several terms are intentionally masked with ***. This masking can cover very few or many of the question words. Clearly, if masked terms are important, the modified question will be impossible to answer. Please indicate the correct answer with one of the following responses: "A", "B", "C", "D" or "E". While "A"-"D" correspond to the answer options provided in the input, "E" represents "I don't know" for questions that do not provide enough information. Respond via "E" if the question is not answerable. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D', 'E'.
question:
Question: What effect does *** of ***, disease, and *** have on a population?  (A) They increase the mutations in a population. (B) They prevent a population from becoming extinct. (C) They increase the rate of population growth. (D) They can limit the growth of the population.
answer:
E.


question:
Question: To safely *** an *** using ***, what should students always do?  (A) Work in large groups. (B) Wear safety goggles. (C) Wear short sleeves. (D) Keep a window open.
answer:
E.


question:
Question: Which system is responsible for getting *** of *** *** and ***?  (A) digestive (B) urinary (C) locomotion (D) circulator.
answer:

E.