If R(t) Is the Position Vector of a Particle in the Plane

Multiple Choice

If r(t) is the position vector of a particle in the plane at time t, find the indicated vector.
-Find the velocity vector.
$\mathbf { r } ( \mathrm { t } ) = \left( - 8 \mathrm { t } ^ { 2 } - 3 \right) \mathbf { i } + \left( \frac { 1 } { 9 } \mathrm { t } ^ { 3 } \right) \mathbf { j }$

A) $v = ( - 16 ) i + \left( \frac { 2 } { 3 } t \right) j$
B) $\mathbf { v } = ( - 16 \mathrm { t } ) \mathbf { i } + \left( \frac { 1 } { 3 } \mathrm { t } ^ { 2 } \right) j$
C) $\mathbf { v } = ( - 16 \mathrm { t } ) \mathbf { i } - \left( \frac { 1 } { 3 } \mathrm { t } ^ { 2 } \right) \mathbf { j }$
D) $\mathbf { v } = \left( \frac { 1 } { 3 } \mathrm { t } ^ { 2 } \right) \mathbf { i } + ( - 16 \mathrm { t } ) \mathbf { j }$