Answer:
Im sure the awnser is option
A. arranged in a regular pattern.
The channel is whatever was used to carry information from
one place to another, or from one person to another.
In this scenario, the channel is e-mail.
I'd go with electricity source. Good luck!!
Answer:

Explanation:
using the law of the conservation of energy:


where K is the spring constant, x is the spring compression, N is the normal force of the block,
is the coefficiet of kinetic friction and d is the distance.
Also, by laws of newton, N is calculated by:
N = mg
N = 3.35 kg * 9.81 m/s
N = 32.8635
So, Replacing values on the first equation, we get:

solving for
:

wavelength = speed/frequency
==> freq. = speed/wavelength = 342.5/0.75 = 456.67 Hz.