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.

[Q]: Question: As the plane dropped altitude, the passengers felt _____. 
 Option1: cooler 
 Option2: warmer 
 Explanation: In the troposphere, temperatures decrease as altitude increases.
[A]: warmer


[Q]: Question: What will happen to Jim's muscle strength if he exercises more then he has in the past? 
 Option1: his muscles will become stronger 
 Option2: his muscles will become weaker 
 Explanation: Aerobic exercise increases the size and strength of muscles in the heart and helps all your muscles develop greater endurance.
[A]: his muscles will become stronger


[Q]: Question: Ian sees an object with many colliding particles, and he compares it to another object with few colliding particles. Which is true about the objects? 
 Option1: the object with many colliding particles has a lower concentration of particles 
 Option2: the object with many colliding particles has a higher concentration of particles 
 Explanation: At higher concentrations, particles of reactants are crowded closer together, so they are more likely to collide and react.
[A]:
the object with many colliding particles has a higher concentration of particles