Electromagnetic waves vary in

a. the speed they travel in a vacuum.

b. wavelength and frequency.

c. the way they reflect.

d. the orientation of their electric and magnetic fields.

I think the answer is D. the orientation of their electric and magnetic fields

A person's risk of sunburn on a certain body part is greater the more directly the Sun's rays hit that body part. If a person is walking outside with the Sun directly overhead, what body part has the greatest risk for sunburn? (Assume that none of the body parts mentioned below are covered by a hat or hair or anything.)