TASK DEFINITION: You are given a question or fill-in-the-blank question, two answer options (Option1 and Option2) and an Explanation. Your task is to find the correct answer (return the string of the correct option, not option1/2) for the given question from the given options and using explanation.
PROBLEM: Question: If Mona is bouncing radar waves off a test car when training to be a policewoman and she notices the frequency of the waves returning to her radar gun is lower then it was before, what is happening to the car she is pointing the gun at? 
 Option1: decreasing in speed 
 Option2: increasing in speed 
 Explanation: A: As the car approaches the radar gun, the reflected microwaves get bunched up in front of the car. Therefore, the waves the receiver detects have a higher frequency than they would if they were being reflected from a stationary object. The faster the car is moving, the greater the increase in the frequency of the waves.

SOLUTION: decreasing in speed

PROBLEM: Question: Eric saw a shell of a snail that was very rare in fossil form. Compared to one that is more common, the rare snail has a shell that is _____ hard. 
 Option1: more 
 Option2: less 
 Explanation: Hard shells fossilize more readily than soft bodied organisms, as they are better at resisting decay, take significantly longer to break down, and have a greater chance of surviving burial under layers of sediment.

SOLUTION: less

PROBLEM: Question: Would Jim's solution become more or less acidic if he increased the concentration of hydrogen atoms in it? 
 Option1: more acidic 
 Option2: less acidic 
 Explanation: With a higher the concentration of hydrogen ions, a solution is more acidic and has a lower pH.

SOLUTION:
more acidic