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: By pouring a pound of salt into a bucket of fresh water, could you cause the density of the water to 
 Option1: increase 
 Option2: decrease? 
 Explanation: Water density increases as salinity and pressure increase, or as temperature decreases.

SOLUTION: increase

PROBLEM: Question: As you travel through the ozone layer the temperatures become 
 Option1: higher 
 Option2: lower 
 Explanation: The stratosphere contains the ozone layer, the temperatures increase as altitude increases.

SOLUTION: higher

PROBLEM: Question: Mark studies rocks for a living. He is curious if rocks deeper in the Earth will be warmer or cooler. If Mark were to take the temperature of a rock that is half a mile into the Earth's surface, and then take the temperature of a rock 1 mile into the Earth's surface, he would find that the rock half a mile into the Earth's temperature is 
 Option1: lower. 
 Option2: higher 
 Explanation: Temperature increases with depth inside the Earth, so melting of rocks is more likely to occur at greater depths.

SOLUTION:
lower.