Answer
Point A should be at a higher electric potential.
Work Step by Step
We can use Equation (24-9) to write an expression for the change in kinetic energy:
$\Delta K = -q~\Delta V = -q~(V_B-V_A)$
An alpha particle has a positive charge.
In order for $\Delta K$ to be positive, then $(V_B-V_A)$ must be negative.
Then $~~V_A \gt V_B$
Point A should be at a higher electric potential.
