Question 2

what agent causes sand dunes to form?

ocean waves

weathering of old rocks in the desert

the wind carries the sand until it runs into an obstacle

gravity

The answer to your question would be:: the wind because it carries the sand until it runs into an obstacle

D. Electrical energy

Explanation:

I assume you are talking about an electrical current.

(These are by what I know and are simplified, not an exact definition)

A. Mechanical energy is energy that something has because of motion.

B. Magnetism is the attracting and repulsing forces between magnets.

C. Geothermal energy is heat inside of the Earth. Used as source of power.

D. Electrical energy is the result of an electric charge.