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 Q]: The ounce, the pound, and the ton are units of  
 (A) time. (B) weight. (C) length. (D) distance.
[EX A]: B

[EX Q]: What form of energy is being used when a person pushes a wooden block across the floor?  
 (A) mechanical (B) magnetic (C) sound (D) electrical
[EX A]: A

[EX Q]: A single human body cell typically contains thousands of  
 (A) genes (B) nuclei (C) chloroplasts (D) bacteria
[EX A]:
A