The above cartoon exhibits a cloud during the mature stage of development of a simple convective thunderstorm. The simplest charge structure sequence in boxes. A, B, C, respectively, can be depicted as follows. Positive charges are shown as +++ and negative charges --- 
Negligible positive charge, $+++, ---$
A simple convective thunderstorm consists of various charge distributions during its mature stage. An understanding of these charge distributions helps us interpret the sequence in the given boxes A, B, and C in the diagram.

Let's analyze the typical charge structure of a mature thunderstorm cloud:
Based on this structure, the simplest charge distribution in boxes A, B, and C would be:
Thus, the correct option is: Negligible positive charge, +++, ---
Therefore, the answer is justified as it explains the typical charge distribution in a mature convective thunderstorm.
The sequence of events in a cloud to ground electrical discharge is