单选题
[填句补文]The black robin（旅鸫）is one of the world‘s rarest birds. It is a small， wild bird， and it lives only on the island of Little Mangere， off the coast of New Zealand. In 1967 there were about fifty black robins there； in 1977 there were fewer than ten. ________.
A.These are the only black robins left in the world.
B.Those that fail to meet the challenges will disappear early.
C.Both represent orders in the classification of life.
D.Detailed studies are going on， and a public appeal for money has been made.
正确答案：A
答案解析：前文说的是The black robin（旅鸫）的现存数量和活动地点。选项A说的是这里成为有The black robin的唯一的地方。所以，选项A是合适的选项。