(c) $\because\ y = e^{(1/2)\log{(1 + \tan^{2}{x)}}\ }\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \$ $\Rightarrow \ \ y = ({\sec^{2}{x)}}^{1/2} = \sec x\$ On differentiating w.r.t. $x$, we get $\frac{dy}{dx} = \sec{x\tan x}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.