There are more and more birds flying to Yancheng for winter every year, ______?

1. A.
   are there
2. B.
   aren't there
3. C.
   are they
4. D.
   aren't they

There are more and more birds flying to Yancheng for winter every year, ________ ?

A. are there

B. aren't there

C. are they

D. aren't they