Suppose an output signal is composed of the product of two other signals $v_{out} = v_1(t)v_2(t)$, where:
$v_1(t) = 5 + 2\cos(2\pi200t)$
$v_2(t) = 2\cos(2\pi1000t)$
Consider the power spectrum of $v_{out}(t)$. Determine the frequencies where the signal power is non-zero.
Select one:
a. 0 and 1000 Hz
b. 200 and 1000 Hz
c. 0, 200 and 1000 Hz
d. 800, 1000 and 1200 Hz