Which of the following is a characteristic of electromagnetic waves? (2 points)

a they are all invisible.
b they have a dual wave-particle nature.
c they can only travel without a medium.
d they are slower than sound waves.

c They can only travel without a medium.

Explanation:

Electromagnetic waves are made up of electric field and magnetic field.

Here electric field will induce magnetic field and magnetic field will induce electric field.

So this type of field do not require any medium and in vacuum or air the speed of electromagnetic waves are same as speed of light

also we have different range of electromagnetic waves out of which a small range of electromagnetic waves is of visible region in which these waves are visible to us.

so correct answer is

c They can only travel without a medium.

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.