VEGETARIANISM

Câu hỏi: Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions.
Until recently, vegetarianism was fairly uncommon in Britain, and it is still considered strange by some. But since the 1960s its popularity has increased greatly, to the (26) _______ that high street stores stock a huge variety of products for vegetarians. The reasons people give for not eating meat are numerous. Perhaps (27) _______ vegetarians do it for moral reasons, arguing that it is wrong to kill. The opposing point of view is that it is natural for US to kill for food, and that we have evolved to do so. Still, there are societies (28) _______ eating meat is not allowed because it is against their religion. There are other good reasons to give up meat, one of which is the inefficiency of livestock farming. A single field of soya bean plants can actually produce 200 times as much protein as the number of cattle which could be raised on the same area of land, so a vegetarian world might be a world without hunger. (29) _______ it is, in theory, cheaper to eat only vegetables, vegetarianism is most popular in richer countries such as Germany and Britain, where many people (30) _______ meat for health reasons. In these countries, at least, it turns out to be a matter of choice rather than necessity
A. which
B. where
C. when
D. what