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]: Routers are basically systems, which connect ____ networks together.\Question: Choose the right answer from options given a) three b) two c) nine d) six
[EX A]: b

[EX Q]: Acoustic guitars come in ____ types.\Question: Choose the right answer from options given a) two b) ten c) one d) four
[EX A]: a

[EX Q]: Skateboards have ____ basic parts.\Question: Choose the right answer from options given a) three b) six c) eight d) one
[EX A]:
a