Let the the position vecor $beR(t)=($:$e^{t}cos(3t),e^{t}sin(3t),0$:$).$ Compute the principal unit normal vector $N(t).$

$A.e^t($:$cos(3t)-3sin(3t),sin(3t)+3cos(3t),0$:$)$

$B.\frac{(\text{:}-sin(3t)-3cos(3t),cos(3t)-3sin(3t),0\text{:})}{e^t\sqrt[\phantom{2}]{10}}$

$c.\frac{(\text{:}cos(3t)-3sin(3t),sin(3t)+3cos(3t),0\text{:})}{\sqrt[\phantom{2}]{10}}$

$D.\frac{(\text{:}{e}^{t}cos(3t),e^{t}sin(3t),0\text{:})}{e^t\sqrt[\phantom{2}]{10}}$

$E.\frac{(\text{:}-sin(3t)-3cos(3t),cos(3t)-3sin(3t),0\text{:})}{\sqrt[\phantom{2}]{10}}$