$r(t)=($:$6cost,30sint$:$),$ for $0t2$

Write the arc length integral and simplify $as$ much $as$ possible. Choose the correct answer below.

$A.L={\displaystyle \underset{0}{\overset{2}{}}}\sqrt[\phantom{2}]{36si{n}^{2}t+900co{s}^{2}t}dt$

$B.L=144{\displaystyle \underset{0}{\overset{2}{}}}(sint+cost)dt$

$C.L=6{\displaystyle \underset{0}{\overset{2}{}}}\sqrt[\phantom{2}]{1+24co{s}^{2}t}dt$

$D.L=144{\displaystyle \underset{0}{\overset{2}{}}}costdt$

The length $of$ the curve $is$ approximately units.

$(Roundto$ two decimal places $as$ needed.$)$