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: Elephants give birth to one calf every ____ to nine years on average.\Question: Choose the right answer from options given a) no b) four c) three d) seven

SOLUTION: b

PROBLEM: Some European countries require ____ years of education.\Question: Choose the right answer from options given a) no b) nine c) six d) three

SOLUTION: d

PROBLEM: Molecules are sometimes in the zero state, sometimes in the ____ state and sometimes in between.\Question: Choose the right answer from options given a) seven b) no c) one d) nine

SOLUTION:
c