Answer:
A. (–3, 4)
Step-by-step explanation:
From the data: (–8, –1), (–8, 4), and (–3, –1) we see that two points have the same y-coordinate, points (–8, –1) and (–3, –1), then the y-coordinate of the fourth vertex is the other y-coordinate, 4. Similarly, we see that two points have the same x-coordinate, points (–8, –1), (–8, 4), then the x-coordinate of the fourth vertex is the other x-coordinate, -3.