Simplify the trigonometric expression. 1/1+ sin theta + 1/1-sin theta A, 2 cos^2 theta B. 2 sec^2 theta C. 2 csc^2 theta D. 2 cot^2 theta A,2 cos^2 theta B. 2 sec ^2 theta C. 2 csc^2 theta D, 2 cot^2 theta .