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 tortoises can retract their head, their ____ limbs and tail into the shell for protection.\Question: Choose the right answer from options given a) no b) one c) two d) four

SOLUTION: d

PROBLEM: Classes play ____ distinct roles in object-oriented programming.\Question: Choose the right answer from options given a) eight b) zero c) two d) no

SOLUTION: c

PROBLEM: Cardiologists offer different estimates, ranging anywhere from ____ to a hundred deaths a year.\Question: Choose the right answer from options given a) five b) one c) zero d) ten

SOLUTION:
a