Answer:
c. hot material must be rising from the Sun's hotter interior
Step-by-step explanation:
Granulation is the grainy appearance of the solar photosphere produced by the top of the convection cells in the sun.
The grainy appearance are produced by granules on the photosphere of the sun and granules are caused by convection currents of plasma within the sun's convection zone.
The interior of these granules are brighter (and thus hotter) than the exterior of the granules which are darker.
So, the granulation pattern that astronomers have observed on the surface of the Sun tells us that hot material must be rising from the Sun's hotter interior.