Answer
(a) (3)
(d) Net displacement is $44.72\,\mathrm{m}$.
Work Step by Step
(a) In the figure, $d$ is the net displacement - given by the hypotenuse of the right triangle formed, as shown.
Since we have one side of the triangle as $40\,\mathrm{m}$, the net displacement is (3) between $40\,\mathrm{m}$ and $60\,\mathrm{m}$.
(b) Net displacement,
$d=\sqrt{40^2+20^2}=44.72\,\mathrm{m}$
