Combined SAT Scores in the United States Could Be Approximated $T ( t ) = - 0.0101 t ^ { 3 } + 0.5856 t ^ { 2 } - 9.6 t + 1038$

Multiple Choice

Combined SAT scores in the United States could be approximated by
$T ( t ) = - 0.0101 t ^ { 3 } + 0.5856 t ^ { 2 } - 9.6 t + 1038$ $( 0 \leq t \leq 23 )$
In the years 1967 - 1990. Here t is the number of years since 1967, and T is the combined SAT score average for the United States. Find all points of inflection of the graph of T, and interpret the result. Round coordinates to two decimal places if necessary.

A) (11.75, 989.90) , (26.90, 1007.45)
B) (19.33, 998.67)
C) (23, 1004.56)
D) (0, 0)
E) (0, 0) , (23, 1004.56)