Find the Third Derivative of the Function $f ( x ) = x ^ { 5 } - 3 x ^ { 4 }$

Multiple Choice

Find the third derivative of the function $f ( x ) = x ^ { 5 } - 3 x ^ { 4 }$ .

A) $60 x ^ { 2 } - 72 x$
B) $30 x ^ { 2 } - 36 x$
C) $60 x ^ { 2 } - 72 x ^ { 2 }$
D) $60 x ^ { 2 } - 36 x$
E) $30 x ^ { 2 } - 36 x$