(c) $\frac{d}{dx}\left\lbrack \frac{e^{x} + 1}{e^{x}} \right\rbrack = \frac{d}{dx}\left\lbrack 1 + e^{- x} \right\rbrack = - e^{- x} = - \frac{1}{e^{x}}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.