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').

Q: Hamsters can live to be three to ____ years old.\Question: Choose the right answer from options given a) four b) two c) three d) nine

A: a
****
Q: Guinea has ____ territories or colonies.\Question: Choose the right answer from options given a) no b) seven c) three d) eight

A: a
****
Q: Streams are ____ dimensional ecosystems.\Question: Choose the right answer from options given a) no b) zero c) one d) three

A:
d
****