Consider likely applicability of Cauchy's Integral Theorem to evaluate the following integral counter clockwise around the unit circle c.
$$I = \oint\limits_{\text{c}} {\sec {\text{z}}} {\text{dz,}}$$   z being a complex variable. The value of $$I$$ will be

A. $$I$$ = 0 : singularities set = $$\phi $$

B. $$I$$ = 0 : singularities set = $$\left\{ { \pm \frac{{2{\text{n}} + 1}}{2}\pi ;\,{\text{n}} = 0,\,1,\,2\,...} \right\}$$

C. $$I = \frac{\pi }{2}:$$  singularities set = $$\left\{ { \pm {\text{n}}\pi ;\,{\text{n}} = 0,\,1,\,2\,...} \right\}$$

D. None of above

Answer: Option A