Answer
Sphere A would be moved to a higher electric potential.
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.
