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 the villagers are living longer, the food source is likely 
 Option1: great 
 Option2: small 
 Explanation: More recently, the death rate has fallen because of the availability of more food and medical advances.
answer:
great


question:
Question: Chris is studying two countries. He finds that China has half as many factories putting out fossil fuels into the air than the United States. Based on this information, the factories in _____ are causing more air pollution. 
 Option1: United States 
 Option2: China 
 Explanation: Because richer nations use more fossil fuels, they also cause more air pollution and global warming than poorer nations do.
answer:
United States


question:
Question: As the train approached the intersection and blew its horn, compressing the wavelengths of the sound, did the frequency of the horn 
 Option1: increase 
 Option2: decrease? 
 Explanation: This means that as wavelengths get shorter, more waves move past a particular spot in the same amount of time.
answer:

increase