Final answer:
The potential difference between points a and d in the figure is -3 V.
Step-by-step explanation:
The potential difference between points a and d in the figure can be determined by summing up the potential differences along the path from a to d. Looking at the given figure, we can see that the potential difference from a to b is 3 V, from b to c is -4 V, and from c to d is 1 V. Adding these potential differences, we get -3 V. Therefore, the potential difference between points a and d is -3 V.