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').

Kabbalists group the simple letters into ____ triplets.\Question: Choose the right answer from options given a) four b) no c) ten d) three
a

Food chains consist of ____ trophic levels.\Question: Choose the right answer from options given a) ten b) three c) one d) four
d

Reptiles Note ____ vertebral regions, cervical, thoracic, lumbar, sacral and caudal.\Question: Choose the right answer from options given a) ten b) six c) five d) nine

c