If $A=\begin{bmatrix}1&\tan\large\frac{\theta}{2}\\-\tan\large\frac{\theta}{2}&1\end{bmatrix}$ and $AB=I$ then $B$=

Question

$\begin{array}{1 1}(A)\;(\cos^2\large\frac{\theta}{2})\normalsize A&(B)\;(\cos^2\large\frac{\theta}{2})\normalsize A'\\(C)\;(\cos^2\large\frac{\theta}{2})\normalsize I&(D)\;\text{None of these}\end{array}$