How Does the Fact That the Surface of the Sun

How does the fact that the surface of the Sun rings like a bell help us better understand the Sun?

A) It tells us how quickly the Sun is expanding with time.
B) It helps us understand the solar interior better.
C) It reveals how rapidly the Sun's magnetic field is changing.
D) It helps us determine the surface temperature of the Sun.
E) It shows the relative gravitational strength of the orbiting planets.