Which transitional word suggests a cause-and-effect relationship?

The word "therefore" is used to indicate a cause-and-effect relationship because it explicitly signals that one event or statement is a consequence of another. It often follows a statement that presents a reason or condition, demonstrating how that reason leads to a particular outcome. For example, in the sentence "It rained heavily; therefore, the ground became muddy," "therefore" clearly connects the cause (the heavy rain) to the effect (the muddy ground).

In contrast, the other options do not imply a direct cause-and-effect link. "Moreover" is typically used to add information, "but" introduces a contrast, and "likewise" indicates similarity rather than causation. Thus, "therefore" is the appropriate choice for conveying a clear cause-and-effect relationship.