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: Many tractors have ____ wheel drive to get extra grip on the hills and in wet conditions.\Question: Choose the right answer from options given a) four b) seven c) five d) two

Answer: a


Question: Whales are divided into ____ categories, based on their teeth.\Question: Choose the right answer from options given a) two b) four c) nine d) ten

Answer: a


Question: Covariance extends The notion of variance to ____ dimensions.\Question: Choose the right answer from options given a) ten b) no c) one d) two

Answer:
d