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]: Human females have ____ X chromosomes.\Question: Choose the right answer from options given a) two b) six c) one d) eight
[EX A]: a

[EX Q]: Fluoroscopy has ____ magnification modes and image capture.\Question: Choose the right answer from options given a) zero b) two c) nine d) eight
[EX A]: b

[EX Q]: Most salamanders have ____ limbs.\Question: Choose the right answer from options given a) four b) three c) nine d) zero
[EX A]:
a