Calculate the Arc Length of the Indicated Portion of the Curve

Multiple Choice

Calculate the arc length of the indicated portion of the curve r(t) .
- $$r ( t ) = \left( 2 \cos ^ { 3 } 5 t \right) \mathbf { j } + \left( 2 \sin ^ { 3 } 5 t \right) \mathbf { k } ; \frac { 3 } { 5 } \pi \leq t \leq \frac { 7 } { 10 } \pi$$

A) 1
B) 3
C) 0
D) 6