The correct answer is: B. are assigned values of 1 or 0 depending on the voltage level.
A digital signal is a signal that can take on only two discrete values, such as 1 and 0. These values are often represented by the voltage levels high and low. Digital signals are used in computers and other electronic devices to represent information.
Option A is incorrect because digital signals can only have two possible levels, not three. Option C is incorrect because digital signals do not have a sinusoidal shape. Option D is incorrect because the frequency of a digital signal is not measured in units of hertz. Option E is incorrect because the correct answer is B.