Nick notices that the young trees he plants follow a typical growth pattern. During the first years of growth he can model the height of a tree with the function
h= -t^2+8t+9
where t is the time in years since being planted and h is the height in inches.

What is the average rate of change, in inches per year, for this function from year 1 to year 4?
3
-1/3
1/3
-3