If `A = 2(sin^6 theta+ cos^6 theta)- 3 (sin^4 theta+ cos^4 theta)` then the value of `3 alpha` such that `cos alpha= sqrt((3+A)/(5+A))` is

Options

A. `180^(@)`
B. `90^(@)`
C. `45^(@)`
D. `135^(@)`

Answer

D