The diagram shows a carrier wave that is used to transmit information. Which best illustrates how the carrier wave would likely appear after pulse modulation?

Second image in your list of possible answers

Explanation:

The second option is what you would expect from modulating a sinusoidal carrier wave of higher frequency after being modulated by a square pulse of lower frequency that allows part of the carrier signal to travel during the time the square signal is constant different from zero, and be absent (flat) during the time the square pulse signal has amplitude zero.

The second line is the best picture of a pulse-modulated carrier.

It would be easy to build a circuit where each pulse ... when it comes along ... just switches the carrier OFF for as long as the pulse lasts.

see earlier answer

find the sum of the two horizontal vectors and the sum of the two vertical vectors

isoceles right angled triangle