Find All the Local Maxima, Local Minima, and Saddle Points

Multiple Choice

Find all the local maxima, local minima, and saddle points of the function.
-f(x, y) = 10xy(x + y) + 4

A) f(10, 0) = 4, local minimum; f(0, 10) = 4, local minimum
B) f(0, 0) = 4, test is inconclusive
C) f(10, 10) = 20,004, local maximum
D) f(0, 0) = 4, saddle point; f(10, 10) = 20,004, local maximum