Figure shows the length, l, in cm, of a sturgeon (a type of fish) as a functionof the time, t, in years.(a) is the function increasing or decreasing? is the graph concave up or concave down? this function is increasing and the graph is concave down.(b) estimate the average rate of growth of the sturgeon betweent= 5andt= 15. giveunits and interpret your answer in terms of the sturgeon. during this five year period, the sturgeon’s length increased at an average rate of 6 cen-timeters per year.