instruction:
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.
question:
22 Sandy is conducting an investigation to find out which food his dog likes best. Which is the manipulated variable in his investigation?  
 (A) The color of his dog's food dish (B) The kind of food he gives his dog (C) The amount of food he gives his dog (D) The time of day he feeds his dog
answer:
B


question:
A tropical rain forest contains many tall trees. Smaller plants with large leaves grow at the base of the tall trees. The large leaves are most likely an adaptation of the plant due to which condition?  
 (A) lack of sunlight (B) lack of oxygen (C) lack of water (D) lack of food
answer:
A


question:
Electricians wear rubber boots and gloves while working with circuits. The main reason for this is because  
 (A) rubber is used as a transmitter. (B) rubber helps to ground them. (C) rubber is a nonconductor. (D) rubber is a conductor.
answer:

C