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.

Ex Input:
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.

Ex Output:
A


Ex Input:
In 1971, the bones of an extinct flying dinosaur were discovered. This kind of discovery helps everyone learn more about  
 (A) impact of humans on Earth. (B) effect of gravity on animals. (C) history of animal species on Earth. (D) likelihood that dinosaurs will reappear.

Ex Output:
C


Ex Input:
As humans grow, their bodies change. Which of these statements explains how humans grow?  
 (A) Cells form a cell wall. (B) Cells increase in size. (C) Cells undergo cell division. (D) Cells merge to become larger.

Ex Output:

C