Question

1. the speed of seismic wave is determined by...

no
density of the material it travels through
gravity
strength of the earthquake
temperature
yes
density of the material it travels through
gravity
strength of the earthquake
temperature

Explanation:

Seismic wave speed depends on the physical properties of the material they propagate through. Higher material density increases wave speed, while higher temperature reduces it. Earthquake strength (magnitude) relates to wave energy, not speed, and gravity has no direct effect on seismic wave speed.

Answer:

Yes - Density of the material it travels through
Yes - Temperature
No - Gravity
No - Strength of the Earthquake