$\text { Find the acceleration vector in terms of } u _ { r } \text { and } u _ { \theta } \text {. }$

Multiple Choice

$\text { Find the acceleration vector in terms of } u _ { r } \text { and } u _ { \theta } \text {. }$
- $\mathrm { r } = 2 \cos 3 \mathrm { t }$ and $\theta = 4 \mathrm { t }$

A) $\mathbf { a } = ( - 50 \sin 3 \mathrm { t } ) \mathbf { u } _ { \mathrm { r } } - 48 \cos 3 \mathbf { t u } _ { \theta }$
B) $\mathbf { a } = ( - 50 \cos 3 \mathrm { t } ) \mathbf { u } _ { \mathrm { r } } + 48 \sin 3 \mathbf { t u } _ { \theta }$
C) $\mathbf { a } = ( - 50 \cos 3 \mathrm { t } ) \mathbf { u } _ { \mathrm { r } } - 48 \sin 3 \mathbf { t u } _ { \theta }$
D) $\mathbf { a } = ( - 50 \cos 4 \mathrm { t } ) \mathbf { u } _ { \mathrm { r } } - 48 \sin 4 \mathrm { tu } _ { \theta }$