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').

Example Input: Plants have three and ____ way branching carying sixteen buds.\Question: Choose the right answer from options given a) seven b) six c) four d) ten
Example Output: c

Example Input: Cleavage is perfect in ____ directions, prismatic.\Question: Choose the right answer from options given a) two b) nine c) three d) seven
Example Output: a

Example Input: Domestic dogs can reproduce at approximately ____ month intervals, though usually less frequently.\Question: Choose the right answer from options given a) two b) three c) seven d) six
Example Output:
d