Find All Critical Numbers for the Function $f(x)=\frac{x^{4}}{4}+1.67 x^{3}-1 x^{2}-24 x+4$

Multiple Choice

Find all critical numbers for the function. State whether it leads to a local maximum, a local minimum, or neither.
- $f(x) =\frac{x^{4}}{4}+1.67 x^{3}-1 x^{2}-24 x+4$

A) Local maximum at -3 ; local minima at -4 and 2
B) Local maxima at 4 and -2 ; local minimum at -3
C) Local maxima at -4 and 2 ; local minimum at -3
D) Local maximum at -4 ; local minimum at 2