Find the absolute extrema of the function, if they exist, over the indicated interval. Also indicate the $x$-value at which each extremum occurs. If no interval is specified, use the real numbers, $(-\infty, \infty)$.
$f(x) = -0.001x^2 + 2.4x - 90$
Select the correct choice below and, if necessary, fill in the answer boxes to complete your choice.
A. The absolute maximum is $\boxed{ }$ at $x = \boxed{ }$ and the absolute minimum is $\boxed{ }$ at $x = \boxed{ }$.
(Use a comma to separate answers as needed.)
B. The absolute maximum is $\boxed{ }$ at $x = \boxed{ }$ and there is no absolute minimum.
(Use a comma to separate answers as needed.)
C. The absolute minimum is $\boxed{ }$ at $x = \boxed{ }$ and there is no absolute maximum.
(Use a comma to separate answers as needed.)
D. There is no absolute maximum and no absolute minimum.