Answer:
C. 3
Explanation:
Amplitude is a way of describing the height of a wave.
Key Terms
First, let's define some key terms of the parts of a wave. The highest point of the wave is the crest. The lowest point of a wave is the trough. The midline or resting point is the horizontal line halfway between the troughs and crests.
In this wave, the crests occur when y = -1 and the troughs occur when y = -7. The midline is y = -4
Finding Amplitude
From a graph, we can say that the amplitude is the distance from the resting position to the crest or trough. In this case, the midline is 3 units away from the crests and troughs. So, answer C is correct.
Since amplitude is a form of distance, it must be positive. This means that answers B and D cannot be correct. Additionally, it would not be a wave if there was no amplitude. An amplitude of 0 means that the graph is just a straight line. This means that A cannot be correct either.