The Position Vector of a Particle Is R(t) $t = 4$

Multiple Choice

The position vector of a particle is r(t) . Find the requested vector.
-The velocity at $t = 4$ for $\mathbf { r } ( \mathrm { t } ) = \left( 8 - 4 \mathrm { t } ^ { 2 } \right) \mathbf { i } + ( 6 \mathrm { t } + 2 ) \mathbf { j } - \mathrm { e } ^ { - 3 \mathrm { t } } \mathbf { k }$

A) $\mathbf { v } ( 4 ) = - 32 \mathbf { i } + 6 \mathbf { j } - 3 \mathrm { e } ^ { - 12 } \mathbf { k }$
B) $\mathbf { v } ( 4 ) = - 32 \mathbf { i } + 6 \mathbf { j } + 3 \mathrm { e } ^ { - 12 } \mathbf { k }$
C) $\mathbf { v } ( 4 ) = 32 \mathbf { i } + 6 \mathbf { j } + 3 \mathrm { e } ^ { - 12 } \mathbf { k }$
D) $\mathbf { v } ( 4 ) = - 16 \mathbf { i } + 6 \mathbf { j } + 3 \mathrm { e } ^ { - 12 } \mathbf { k }$