Which convention did the 15th Convention take place prior to?

The correct answer is based on the sequence of conventions. The 15th Convention occurs before the 16th Convention in a chronological lineup. This is a straightforward numerical relationship, where each convention follows consecutively from the previous one. Therefore, it is logical to conclude that the 15th Convention takes place prior to the next one, which is the 16th Convention.

In the context of the other options, the 14th Convention is actually the one that comes before the 15th, while the 17th and 18th Conventions come after the 15th in this succession. Thus, the question is focused specifically on the immediate successor of the 15th Convention, which is the 16th.