Given a sentence with a missing word, pick the answer option that best fills out the missing word in the sentence. Indicate each answer with its index ('a', 'b', 'c', 'd').
--------
Question: Cows can be up to ____ times more active than normal while in heat.\Question: Choose the right answer from options given a) eight b) nine c) two d) six

Answer: a


Question: Malignant tumors are more dangerous, and survival times can range from ____ months to several years.\Question: Choose the right answer from options given a) one b) no c) ten d) six

Answer: d


Question: Humanity is responsible for ____ or six billion tons a year.\Question: Choose the right answer from options given a) one b) no c) eight d) five

Answer:
d