Which of the following statements best describes a difference between mechanical waves and electromagnetic
waves?

a. Mechanical waves can travel in any direction, while electromagnetic waves travel only in one direction.

b. Mechanical waves travel only at the speed of light, while electromagnetic waves can travel at many different speeds.

c. Mechanical waves can produce colored light, while electromagnetic waves cannot.

d. Mechanical waves travel only through a medium, while electromagnetic waves can also travel through a vacuum.