How do scientists know the Earth's outer core is liquid? Question 7 options:

A Drill holes to the core.

B The outer core isn't liquid.

C Satellites have taken x-rays of Earth

D Earthquake waves.

D Earthquake waves.

Explanation:

Scientists figured out that the outer core must be liquid because S waves do not pass through it, but P waves do. ... Thus by observing many seismic waves from many earthquakes all over the world, scientists have been able to work out the density of different parts of the Earth