Finding average rate of change

Find the average rate of change of a function over a given interval.

Problem

Consider the function h whose graph is shown below.
What is the average rate of change of h over the interval 5, is less than or equal to, t, is less than or equal to, 9?
Give an exact number.
space
On which interval does h, left parenthesis, t, right parenthesis have an average rate of change of zero?
Please choose from one of the following options.