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 Piedmont and Coastal Plains regions in Maryland produce crops such as corn, soybeans, wheat, tobacco, tomatoes, and apples. Which environmental factor most likely influences which crops are grown in these regions?  
 (A) soil quality (B) wind speeds (C) bird migration (D) water temperature
[EX A]: A

[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]: A scientist plans a project to determine the effect of rain on the formation of caves. An area of rock has been chosen as the site for the investigation. How often should the scientist measure the changes in the rock?  
 (A) every day (B) every week (C) every month (D) every year
[EX A]:
D