Teacher: 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').
Teacher: Now, understand the problem? If you are still confused, see the following example:
Female snakes incubate eggs inside of their bodies, giving birth to live young of ____ or more. \Question: Choose the right answer from the options given a) five b) zero c) seven d) ten
Solution: d
Reason: Snakes give birth to minimum ten young ones so ten is a correct answer.

Now, solve this instance: Harpists spend ninety percent of their lives tuning their harps and ____ percent playing out of tune.\Question: Choose the right answer from options given a) ten b) two c) nine d) three
Student:
a