A Hertzsprung-Russell diagram is shown below Based on this diagram, which type of stars would belong to spectral class M and have the highest luminosity?

A) Main sequence stars

B) Giants

C) White dwarfs

D) Supergiants

When can a theory be modified if a new type of technology allows for new observations that raise new questions? a-immediately, while the questions about the theory are being asked b-after new hypotheses related to the theory are tested in experiments c-only after the new observations disprove all parts of the theory d-while scientists begin to think about how the theory could improve