The correct option that would support the student's claim (that magnetic forces exist between the balloons) is actually none of them, because the scenario involves electric forces rather than magnetic forces.
When two positively charged balloons are brought close to each other, they will repel each other due to like charges repelling. Therefore, the correct answer to the behavior of the balloons would be:
d) The balloons will repel each other.
However, it's important to note that this scenario does not support the student's claim about magnetic forces, as the forces involved are electrostatic.