Find the Unit Tangent Vector $\mathbf { T } ( t )$

Multiple Choice

Find the unit tangent vector $\mathbf { T } ( t )$ for $\mathbf { r } ( t ) = 6 t \mathbf { i } + 6 t \mathbf { j } + 7 t \mathbf { k }$ at $t = 2$ .
Select the correct answer.

A) $\frac { 3 } { 121 } \mathbf { i } + \frac { 3 } { 121 } \mathbf { j } + \frac { 7 } { 242 } \mathbf { k }$
B) $\frac { 6 } { 11 } \mathbf { i } + \frac { 6 } { 11 } \mathbf { j } + \frac { 7 } { 11 } \mathbf { k }$
C) $12 \mathbf { i } + 12 \mathbf { j } + 14 \mathbf { k }$
D) $6 \mathbf { i } + 6 \mathbf { j } + 7 \mathbf { k }$