Assume that all four H-R diagrams below represent a star in different stages of its life, after it starts to fuse hydrogen in its core. Rank the HR diagrams based on when each stage occurs, from first to last.

The right answer for the question that is being asked and shown above is that: "1-4-3-2." (main sequence-->red giant-->supergiant-->white dwarf). Assume that all four H-R diagrams below represent a star in different stages of its life, after it starts to fuse hydrogen in its core.