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: Sexual maturity is reached at about ____ years of age.\Question: Choose the right answer from options given a) five b) ten c) no d) two

SOLUTION: d

PROBLEM: Background radiation comes from ____ sources.\Question: Choose the right answer from options given a) zero b) three c) four d) no

SOLUTION: b

PROBLEM: Codons are sets of ____ adjacent nucleotides which code for an amino acid.\Question: Choose the right answer from options given a) three b) seven c) four d) no

SOLUTION:
a