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: A chemist compared two substances in the lab. Which substance will have a higher concentration of hydrogen ions? 
 Option1: the substance with the higher pH 
 Option2: the substance with the lower pH 
 Explanation: The lower the pH value is, the greater is the concentration of hydrogen ions and the stronger the acid.

SOLUTION: the substance with the lower pH

PROBLEM: Question: Do electric cars pollute more or less than gas cars? 
 Option1: more 
 Option2: less 
 Explanation: Plug-in hybrids run for a longer time on electricity and so are less polluting than regular hybrids.

SOLUTION: less

PROBLEM: Question: Tessa took a long run and noticed her veins were _____. 
 Option1: smaller 
 Option2: larger 
 Explanation: Increasing the diameter of the blood vessels increases the amount of blood and heat that moves near the skins surface.

SOLUTION:
larger