Correct answer only !

in order to do work, the force vector must be

Work = force x distance

So we are looking for something related to displacement.

The work done must also be done in the same direction, parallel to the displacement, and therefore in the same direction of the motion as well.

So:

In order to do work, the force vector must be in the same direction as the displacement vector and the motion.

explanation:

considering the bohr theory, the type of connection that requires the transfer the answer conuldn't be right

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.