Mathematics

Problem

Which one of the following limit does not have value unity? (a)

\lim_{x \rightarrow 0} \frac{\sin(\tan x)}{\sin x}

(b)

\lim_{x \rightarrow \frac{\pi}{2}} \frac{\sin(\cos x)}{\cos x}

(c)

\lim_{x \rightarrow 0} \frac{\sqrt{1+x} - \sqrt{1-x}}{x}

(d)

\lim_{x \rightarrow 0} \left( \frac{\sin x}{x} \right)^{\frac{1}{x^2}}