Let $\mathbf { r } ( t ) = - 2 t \mathbf { i } - \cos ( t ) \mathbf { j } + \sin ( t ) \mathbf { k }$

Multiple Choice

Let $\mathbf { r } ( t ) = - 2 t \mathbf { i } - \cos ( t ) \mathbf { j } + \sin ( t ) \mathbf { k }$ Then the unit normal vector $\mathbf { n } ( 0 )$ is

A) $- \mathbf { i }$
B) k
C) i
D) j
E) $- \mathbf { k }$