Step-by-step explanation:
If we graph elevation vs time, the rate of change is the slope of the line.
At t = 0, h = -90.
At t = 15, h = -20.
m = (-20 − (-90)) / (15 − 0)
m = 70/15
m = 4.67
The closest answer is B. The elevator traveled upward at a rate of 4 feet per second.