Answer
$2\sqrt6$
Work Step by Step
The distance $d$ from $P_1(x_1,y_1,z_1)$ to $P_2(x_2,y_2,z_2)$ is given by the formula $d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2+(z_2-z_1)^2}$.
Hence here $d=\sqrt{(4-2)^2+(1-(-3))^2+(-1-(-3))^2}=\sqrt{2^2+4^2+2^2}=\sqrt{4+16+4}=\sqrt{24}=2\sqrt6$