1. **Problem statement:** We have an electric field $E = 9$ V/m directed in the negative $y$-direction. We want to find the potential difference $V_{AB} = V_A - V_B$ between points $A(-2,0)$ and $B(1,-3)$. 2. **Formula and concept:** The potential difference between two points in an electric field is given by $$V_{AB} = -\vec{E} \cdot \vec{d}$$ where $\vec{d} = \vec{r}_A - \vec{r}_B$ is the displacement vector from point B to point A. 3. **Calculate displacement vector $\vec{d}$:** $$\vec{d} = (x_A - x_B, y_A - y_B) = (-2 - 1, 0 - (-3)) = (-3, 3)$$ 4. **Electric field vector:** Since $E$ points in the negative $y$-direction, $$\vec{E} = (0, -9)$$ 5. **Calculate dot product $\vec{E} \cdot \vec{d}$:** $$\vec{E} \cdot \vec{d} = 0 \times (-3) + (-9) \times 3 = -27$$ 6. **Calculate potential difference:** $$V_{AB} = -\vec{E} \cdot \vec{d} = -(-27) = 27$$ 7. **Interpretation:** The potential at point A is 27 volts higher than at point B. **Final answer:** $\boxed{27\text{ V}}$ (Option A)