instruction:
You are given a science question (easy-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.
question:
Human DNA includes a class of genes called "tumor suppressors." What do these genes do in bone cells?   
 (A) They restrict cell cycle progression in bone cells. (B) They promote the rapid development of bone cells. (C) They limit the number of bones in the human body. (D) They enable phosphorus and calcium to enter bone cells.
answer:
A


question:
Sal is looking at a map of Massachusetts. He has measured the distance, in inches, from Boston to Salem on the map. He wants to know how many actual miles the inches represent. What feature of the map should he look for?  
 (A) key (B) scale (C) legend (D) compass
answer:
B


question:
Which of these is the best example of organisms interacting with each other in an ecosystem?  
 (A) a buffalo drinking water (B) a bear catching a fish (C) a rabbit running across the sand (D) a pig rolling in the mud
answer:

B