The period of oscillation of a simple pendulum is $T= 2 \pi \sqrt {\large\frac{L}{g}}$. Measured value of L is $20.0\;cm$ known to 1mm accuracy and time for 100 oscillations of the pendulum is found to be 90 s using a wrist watch of 1 s resolution . The accuracy in the determination of g is :

Question

$\begin{array}{1 1} 5 \% \\ 2 \% \\ 3 \% \\ 1\% \end{array}$