Explanation:

- Statement I is incorrect. The hypocenter is the point inside the Earth where an earthquake originates, not on the surface. The correct term for the surface point directly above the hypocenter is the "epicenter."

- Statement 2 is correct. Earthquake waves generally travel faster through denser materials because denser materials can transmit energy more efficiently.

- Statement 3 is correct. P waves (primary waves) are the fastest type of seismic wave and are the first to be detected by seismographs on the surface.

Therefore, the correct answer is:

Option 2: 2 and 3