Consider the following data and choose the correct option.
1. The time period of a simple pendulum, whose bob is a hollow metallic sphere is T.
2. The time period of a simple pendulum is T1, when the bob is filled with sand,
3. The time period of a simple pendulum is T2, when it is filled with mercury and
4. The time period of a simple pendulum is T3, when it is half-filled with mercury as shown.