$v_x =\large\frac{dx}{dy}$$=24 \cos 6t$
$v_y =\large\frac{dy}{dt}$$=24 \sin 6t$
$v=\sqrt {{v_x}^2+{v_y}^2}$
$\quad=24 m/s^2$
Since $v$- speed is constant.
distance traversed in 4 second is
$s=v \times t$
$s=24 \times 4$
$s=96 m$
Hence a is the correct answer.