Stars that are actively fusing hydrogen in their cores occupy which region of the hertzsprung-russell diagram?
a. main sequence
b. white dwarfs
c. subgiants
d. giants

This chart shows characteristics of three different types of waves. which statement is best supported by the information in the chart? wave x and wave y are mechanical waves, and wave z is an electromagnetic wave. wave x and wave y are electromagnetic waves, and wave z is a mechanical wave. wave x and wave z are electromagnetic waves, and wave y is a mechanical wave. wave x and wave z are mechanical waves, and wave y is an electromagnetic wave.