How long does it take the seismic waves to pass directly through the Earth?

It ranges from 2 to 13 km/s depends upon composition.

Explanation:

The velocity of seismic waves are different throughout the earth because of different composition of the layers inside the earth. Velocity of seismic waves increases with depth and it is approximately 2 to 8 km/s in the Earth's crust whereas, 13 km/s in the deep mantle so it means the velocity of seismic waves is higher in the mantle as compared to earth's crust due to different composition of layers between the mantle and earth crust.

it sounds like either a or c

answer; ///(true)/// fusion occurs in the sun's core;