On which interval does h(x) have an average rate of change of zero

In the interval (-∞, -5)

Step-by-step explanation:

Average rate of change of any graph is represented by the slope of the function in the given interval.

Rate of change =

= change in the y-coordinates

= change in the x-coordinates

If = 0, then the rate of change will be zero in that interval

From the graph attached,

From x = -∞ to x = -5, we find a flat line, showing

Therefore, average rate of change of h(x) in the interval (-∞, -5) is zero.