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').

Banks hold ____ excess reserves and the public holds no currency.\Question: Choose the right answer from options given a) two b) seven c) ten d) no
d

Earthworms have ____ pairs of hearts.\Question: Choose the right answer from options given a) seven b) five c) one d) no
b

Pyridine is aromatic with ____ pi electrons in a cyclic, conjugated pi-orbital system.\Question: Choose the right answer from options given a) five b) six c) eight d) seven

b