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]: Ascidian tunicates come in ____ main forms.\Question: Choose the right answer from options given a) three b) zero c) four d) eight
[A]: a


[Q]: Japan is a highly urbanised country, with approximately three in every ____ people living in cities.\Question: Choose the right answer from options given a) seven b) two c) four d) eight
[A]: c


[Q]: Habitat destruction is a concern for all ____ gorilla subspecies.\Question: Choose the right answer from options given a) no b) four c) three d) five
[A]:
b