Question

which best describes electromagnetic waves?
sound waves that can only travel in a medium
mechanical waves that travel as ripples in water
transverse waves made up of electric and magnetic fields
longitudinal waves made up of vibrations that move through matter

Explanation:

Electromagnetic waves are transverse waves. They are composed of oscillating electric and magnetic fields. They do not need a medium to travel (unlike sound or mechanical waves which require a medium like air, water etc. for their propagation).

Answer:

transverse waves made up of electric and magnetic fields