To do a net drawing you have to cut the object so you can display all its sides in 2D.
An orthographic drawing is 3D object drawn in 2D from 3 points of view: front, left/right and top.
An isometric drawing is 3D object displayed in 2D by rotating it 45 degrees to left/right and 45 degrees upward/downward.
So the correct answers are:
A - net, B - orthographic, C & D - isometric.
