Gonna be easy

Classical Mechanics Level 3

The period of oscillation of a simple pendulum is $T=2\pi \sqrt{\frac{L}{g}}$ . Measured value of $L$ is $20cm$ known to $1mm$ accuracy and time for $100$ oscillation is found to be $90s$ using a wristwatch of $1s$ resolution. The accuracy in determination of $g$ is:

1% 5% 2% 3%