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.

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
C

Which characteristic of sound makes it possible for bats to fly in the dark without hitting any objects?  
 (A) refraction (B) reflection (C) conduction (D) amplification
B

A student sets a block at the top of a wooden ramp. The student pushes the block. As the block slides down the ramp, it slows down and then comes to a stop. What force causes the block to slow down?  
 (A) the force of gravity (B) the force of friction (C) the force of magnetism (D) the force of the student's push

B