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').

[EX Q]: Midrange drivers are used in multi-way speakers with ____ or more driver sizes.\Question: Choose the right answer from options given a) one b) five c) four d) three
[EX A]: d

[EX Q]: Streptomyces are of special interest for ____ reasons.\Question: Choose the right answer from options given a) nine b) seven c) four d) two
[EX A]: d

[EX Q]: B cells can receive stimulation in ____ ways.\Question: Choose the right answer from options given a) one b) two c) five d) zero
[EX A]:
b