TASK DEFINITION: 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').
PROBLEM: Many scientists believe the neutrino has ____ mass at all.\Question: Choose the right answer from options given a) eight b) zero c) two d) no

SOLUTION: d

PROBLEM: Voles are prolific breeders and can produce four to ____ litters a year.\Question: Choose the right answer from options given a) four b) two c) six d) three

SOLUTION: c

PROBLEM: Hydroplanes have ____ or more wetted surface areas.\Question: Choose the right answer from options given a) two b) four c) ten d) one

SOLUTION:
a