instruction:
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:
Question: When a star is nearing a planet, the star will be pulled into it if the gravitational force is 
 Option1: weaker 
 Option2: stronger 
 Explanation: The closer objects are to each other, the stronger the gravitational force between them.
answer:
stronger


question:
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.
answer:
the substance with the lower pH


question:
Question: Carl is studying climate change, and notes that more ultraviolet radiation is being trapped, which means the earth will be 
 Option1: cooler 
 Option2: warmer 
 Explanation: If there are more greenhouse gases in the atmosphere, more ultraviolet radiation will be trapped and the Earth will heat up.
answer:

warmer