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: Mike wants his voice to travel slowly, so he will speak in a room that is 
 Option1: colder 
 Option2: warmer 
 Explanation: For a given medium such as air, sound has a slower speed at lower temperatures.

SOLUTION: colder

PROBLEM: Question: If Jim is transmitting electricity through a wire and he reduces the size of that wire, the electrons move through it 
 Option1: easier 
 Option2: harder 
 Explanation: A thinner wire is more difficult for electrons to move through than a thicker wire.

SOLUTION: harder

PROBLEM: Question: If Mona is filling a balloon with helium and she adds more gas to it, what happens to the likelihood that the helium particles will collide with each other? 
 Option1: more likely 
 Option2: less likely 
 Explanation: At higher concentrations, particles of reactants are crowded closer together, so they are more likely to collide and react.

SOLUTION:
more likely