a
$(a)$ Time period of a simple pendulum depends on its amplitude as,
$T=2 \pi \sqrt{\frac{l}{g}} \cdot\left(1+\frac{\theta_{0}^{2}}{16}\right)$
where, $\theta _{0}=$ angular a mplitude from mean position. Clearly, $T$ increases with $\theta$ and its relation is parabolic. Its variation is as shown below in the figgure.
