Q39:

The survival of a rare New Zealand species of mistletoe that produces spectacular sprays of scarlet flowers is threatened both because their leaves are extremely tasty to a voracious opossum species and also because their flowers are pollinated by two species of birds whose populations are in decline.

1. is threatened both because their leaves are extremely tasty to a voracious opossum species and also because their
2. is threatened both because its leaves are extremely tasty to a voracious opossum species and because its
3. is threatened both because its leaves are extremely tasty to a voracious opossum species and also its
4. are threatened both because its leaves are extremely tasty to a voracious opossum species and its
5. are threatened both because their leaves are extremely tasty to a voracious opossum species and because their

答案是B，我选了A。

想请教species of mistleteo对应的代词应该是单数还是复数？

原文已经说明了 a (rare New Zealand) species, 单数

spe‧cies W3 plural species [countable]

HB a group of animals or plants whose members are similar and can breed together to produce young animals or plants:

Seven species of birds of prey have been observed.

pandas and other endangered species (=ones that may soon no longer exist)