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]: A radio station broadcasting across a large area is experiencing thunderstorms. How will the radio waves from the station be affected?
(A) wavelength will be increased (B) amplitude will be unchanged (C) frequency will be distorted (D) speed will be decreased
[EX A]: C

[EX Q]: Russell wants to observe changes in nature over the next few months. What can a thermometer help Russell investigate?
(A) rainfall amounts each week (B) tiny organisms in pond water (C) the high temperatures each day (D) the amount of growth in a plant
[EX A]: C

[EX Q]: Which is an SI unit for density?
(A) lb (B) kg (C) lb/ft^3 (D) kg/m^3
[EX A]:
D