In the H-R Diagram Shown in Figure 13-31b in the Text

In the H-R diagram shown in Figure 13-31b in the text, the brightest stars in the Pleiades cluster are not on the main sequence but away from it toward the upper right. Explain.

A) The brightest stars have not yet reached the main sequence and are in the T Tauri phase.
B) The brightest stars have already evolved through the red giant phase and have now returned to the blue giant phase on their way to the white dwarf phase.
C) The brightest stars have already become white dwarf stars, as shown by their position.
D) These blue supergiant stars have already begun to evolve toward the red supergiant phase.