Help its EZ question just need clarificaion help with which choice.

The graph below shows the height an elevator travels, y, in x seconds:

What is the rate of change for the relationship represented in the graph?

A. fraction 1/15
B.fraction 1/14
C.14
D. 15

So obviously its either A. or D. because its moving on the y-axis by 15 but idk which one, when do you use a fraction as the rate of change and when do you use a regualr whole number??? Plz explain to me.

Help its EZ question just need clarificaion help with which choice The graph below shows the height an elevator travels y in x seconds What is the rate of chang class=