The frequency of a wave determines which of the following?
loudness
reflection
energy
pitch

The wave frequency determines the pitch of the sound.

Option D

Explanation:

The wave frequency determines the pitch of the sound as the sound wave has the frequency which is sensibly understood by the human ear as the pitch. Pitch has two category, high pitch and low pitch.

A high pitch sound is one which has the rapid or more frequent oscillation and on the other hand, low pitch sound is the one which has slow or less frequent oscillation in the sound wave.

c because the action was the roller coaster reaches bottom of hill (action) reaction would be blood tends to drain away from head

hope this !

hypothesising or postulating