Which type of diagram most closely resembles how events unfold in reality? why? why might historians choose to use another diagram instead?

The most clear layout for organizing events is a timeline. Timelines allow events to be organized in sequence according to when they occur. This type of graph portrays events according to when and where they happen. Another type of diagram that may be useful for History is that of a roadmap. Compared to a timeline, a roadmap graph is used to explain steps, and guidelines as opposed to present events in a chronological order.

c, to compete

yup! you are correct it is b.