$\text { For the curve } r ( t ) \text {, write the acceleration in the form aTT } + \text { anN. }$

Multiple Choice

$\text { For the curve } r ( t ) \text {, write the acceleration in the form aTT } + \text { anN. }$
- $$\mathbf { r } ( \mathrm { t } ) = ( \mathrm { t } + 1 ) \mathbf { i } + ( \ln ( \sec t ) - 9 ) \mathbf { j } + 9 \mathbf { k } , - \pi / 2 < \mathrm { t } < \pi / 2$$

A) $\mathbf { a } = ( \cos t ) \mathbf { T } + ( \cos t ) \mathbf { N }$
B) $a = \left( \sec ^ { 2 } t \right) T + ( \cos t ) \mathbf { N }$
C) $\mathbf { a } = ( \csc t ) \mathbf { T } + ( \sec t ) \mathbf { N }$
D) $\mathbf { a } = ( \sec t \tan t ) \mathbf { T } + ( \sec t ) \mathbf { N }$