Answer
The work done by our force is the same for all three paths.
Work Step by Step
We can write a general equation for the electric potential around a point charge:
$V = \frac{1}{4\pi~\epsilon_0}~\frac{q}{r}$
Sphere B is positively charged so $V \gt 0$ at all points.
As $r$ decreases, the magnitude of $V$ increases.
Therefore, sphere A would be moved to a higher electric potential.
That is $~~V_f \gt V_i$
We can find an expression for the work done by our force:
$Work = \Delta U = q_A~\Delta V = q_A~(V_f-V_i)$
Note that the work done by our force is not dependent on the specific path.
Since the initial position and the final position are the same for all three paths, the work done by our force is the same for all three paths.
