(d)

Given function

$f(x)=\left[\begin{array}{cc} \frac{\sin \left(x^2\right)}{x} & , x \neq 0 \\ 0 & , \text { if } x=0\end{array}\right.$

then $\lim _{x \rightarrow 0} f(x)=\lim _{x \rightarrow 0} \frac{\sin x^2}{x}=\lim _{x \rightarrow 0}$

$x \frac{\sin x^2}{x^2}=0=f(0)$

Hence, $f(x)$ is continuous at $x=0$

Now, for differentiability

$RHD ($ at $x=0)$

$=\lim _{h \rightarrow 0} \frac{f(0+h)-f(0)}{h}=\lim _{h \rightarrow 0} \frac{\sin h^2}{h^2}=1$

and $LHD$ (at $x=0)$

$=\lim _{h \rightarrow 0} \frac{f(0-h)-f(0)-\lim _{h \rightarrow 0} \sin h^2}{-h}=1$

So, $f(x)$ is differentiable at $x=0$

$\therefore \quad f^{\prime}(x)=\left[\begin{array}{cc}2 \cos \left(x^2\right)-\frac{\sin x^2}{x^2} & , \text { if } x \neq 0 \\ 1 & , \text { if } x=0\end{array}\right]$ $\because \lim _{x \rightarrow 0} f^{\prime}(x)=\lim _{x \rightarrow 0}\left[2 \cos \left(x^2\right)-\frac{\sin x^2}{x^2}\right]$ $=2-1=1$ $\therefore \lim _{x \rightarrow 0} f^{\prime}(x)=f^{\prime}(0)$ So,f $f(x)$ is differentiable and the