Diagram B is the best choice for explaining plate tectonics to someone based on its simplicity, accuracy, emphasis on boundaries, and effective use of visuals.
The diagram is clear and uncluttered, with only the essential elements needed to explain the concept. It shows the Earth's major tectonic plates, labeled with their names, and arrows indicating their direction of movement.
The diagram accurately represents the relative sizes and positions of the plates, as well as the different types of plate boundaries (divergent, convergent, and transform).
The diagram highlights the three main types of plate boundaries with different line styles and colors: