The Tangential Component $a _ { \mathrm { T } } ( t )$

Multiple Choice

The tangential component $a _ { \mathrm { T } } ( t )$ of the acceleration of a particle moving along the curve $\mathbf { r } ( t ) = t ^ { 2 } \mathbf { i } - t \mathbf { j } - t ^ { 2 } \mathbf { k }$ is

A) $\sqrt { 56 }$
B) $\sqrt { 8 t ^ { 2 } + 1 }$
C) 0
D) $\sqrt { 65 }$
E) $\frac { 8 t } { \sqrt { 8 t ^ { 2 } + 1 } }$