Answer
See work below.
Work Step by Step
Case A. The temperature increases (see the horizontal axis of the H-R diagram). The luminosity stays the same (see the vertical axis of the H-R diagram). The size decreases (smaller stars are found in the lower left).
Case B: The temperature stays the same (see the horizontal axis of the H-R diagram). The luminosity decreases (see the vertical axis of the H-R diagram). The size decreases (smaller stars are found in the lower left).
Case C: The temperature decreases (see the horizontal axis of the H-R diagram). The luminosity increases (see the vertical axis of the H-R diagram). The size increases (larger stars are found in the upper right).
