Question

1. what is white noise?

noise made up of many different frequencies
noise made from the highest frequency
noise made from a single high and a single low frequency
noise made from the lowest frequency

Explanation:

White noise is a random signal (or process) with a flat power spectral density. This means it has equal intensity at different frequencies, similar to white light which contains all visible frequencies. So it is made up of many different frequencies.

Answer:

noise made up of many different frequencies