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.

Question: Tanya has a substance with mass 10kg. Logan has a substance with mass 5kg. If both substances are the same size, who has the less dense substance. 
 Option1: Tanya 
 Option2: Logan 
 Explanation: If we have two materials with the same volume, the material with a higher mass will be more dense.
Logan

Question: Lana is watching two waterfalls. The first waterfall is very steep, and the other is just a slope. The waterfall which will have the least erosion at the bottom is the one with the water which falls 
 Option1: slower 
 Option2: faster 
 Explanation: Water flowing over a steeper slope moves faster and causes more erosion.
slower

Question: Mel is running down the street for exercise. As Mel's heart rate increases, Mel's blood flow 
 Option1: decreases 
 Option2: increases 
 Explanation: Warming up exercises increases the blood flow to the muscles and increases the heart rate.

increases