Find the Slope of the Graph of the Function at the Given

Multiple Choice

Find the slope of the graph of the function at the given value. $f ( x ) = 4 ( 5 x + 6 ) ^ { 2 }$ at $x = 3$

A) $f ^ { t } ( 3 ) = 840$
B) $f ^ { t } ( 3 ) = 360$
C) $f ^ { t } ( 3 ) = 42$
D) $f ^ { t } ( 3 ) = 168$
E) $f ^ { t } ( 3 ) = 210$