Let $f$ be function
$f(x)=
\begin{cases}
\frac{\tan x}{x}, & x \ne 0 \\
1, & x=0
\end{cases}$
Assertion: $x=0$ is point of minima of $f$
Reason: $f'(0)=0$
(a) Assertion is true, Reason is true, and Reason is the correct explanation of the Assertion.
(b) Assertion is true, Reason is true, but Reason is not the correct explanation of the Assertion.
(c) Assertion is true, but Reason is false.
(d) Assertion is false, but Reason is true.