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').

Female cats can go into heat for the first time as early as ____ months of age.\Question: Choose the right answer from options given a) four b) zero c) five d) eight
c

Potassium helps maintain fluid regulation and normal pH. All ____ help normalize.\Question: Choose the right answer from options given a) three b) six c) two d) one
a

All pollen grains develop initially in groups of ____ called tetrads.\Question: Choose the right answer from options given a) seven b) no c) four d) zero

c