Hello! I need help with this question. I have an answer but I wanted to make sure it's correct. Thanks!

Question

Question: Which of the following is NOT a trigonometric identity?

Answers Given:
A.) 1-cos^2x=sin^2x
B.) sin^2x+1=cos^2x
C.) 1+cot^2x=csc^2x
D.) sec^2x-1=tan^2x

My answer: C.)

Answer 1

B.)

Becouse :

sin ^ 2 x + cos ^ 2 x = 1

and

sin ^ 2 x - 1 = cos ^ 2 x

Other 3 expression are identity.

Answer 2

B.)

Correction.

sin ^ 2 x + cos ^ 2 x = 1

and

1 - sin ^ 2 x = cos ^ 2 x

But Answer B.)