Question

Identities and proof help please (:

Which of the following is NOT an identity

A) 1+cos^2 x / sin^2 x =1
B) tan^2 x=sec^2 x-sin^2 x-cos^2 x
C) (cosx+sinx)^2 = 1+2cosxsinx
D) (tanx+cotx)^2= csc^2 x + sec^2 x