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').

[Q]: Alleles fall into ____ classes based on somatic, gonadal and dauer phenotypes.\Question: Choose the right answer from options given a) ten b) six c) eight d) no
[A]: b


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


[Q]: Kiloliters are ____ orders to the left of deciliters.\Question: Choose the right answer from options given a) eight b) five c) four d) two
[A]:
c