To show a cause and effect relationship, a speaker can best utilize option C: Show what brought about an event and what results it had. This approach directly connects a cause to its effect, illustrating how one event leads to another.
While option A (Listing events in order) might imply a sequence, it does not necessarily convey the causal relationships. Option B (Discussing similarities and differences) focuses on comparative analysis rather than causation, and option D (Identifying a problem and solutions) may elaborate on consequences but doesn't specifically establish the direct cause-and-effect link. Therefore, option C is the most effective for clearly demonstrating causality.