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: When everyone can eat what happens to the number of people that die?
Option1: increases
Option2: decreases
Explanation: With better food and less chance of disease, the death rate fell.

SOLUTION: decreases

PROBLEM: Question: Mona is a scientist studying erosion at a university. She is observing a river. If she starts taking erosion measurements at the mouth of the river and moves up to the head of the river, what will she find happens as the slope gets steeper?
Option1: erosion decreases
Option2: erosion increases
Explanation: Water flowing over a steeper slope moves faster and causes more erosion.

SOLUTION: erosion increases

PROBLEM: Question: If Jim turns the thermostat up in his room while listening to music, what will happen to the speed of the sound waves in the room?
Option1: they will speed up
Option2: they will slow down
Explanation: For a given medium, sound has a slower speed at lower temperatures.

SOLUTION:
they will speed up