The Number of People Who Donated to a Certain Organization $D ( t ) = - 10.82 t ^ { 3 } + 209.508 t ^ { 2 } - 167.402 t + 9774.134$

Multiple Choice

The number of people who donated to a certain organization between 1975 and 1992 can be modeled by the equation $D ( t ) = - 10.82 t ^ { 3 } + 209.508 t ^ { 2 } - 167.402 t + 9774.134$ donors, where t is the number of years after 1975. Find the inflection point(s) from $t = 0$ through $t = 17$ , if any exist.

A) There are no inflection points from $t = 0$ through $t = 17$ .
B) There is one inflection point at $t = 6.45$ .
C) There are inflection points at $t = 0$ and $t = 17$ .
D) There is one inflection point at $t = 0.15$ .
E) There are inflection points at $t = 0$ , $t = 0.15$ , and $t = 17$ .