Please I need help I have 8 assignments and if I don't do them I will likely fail my math class and get whooped in the butt so please for the love of God help me

Select the correct answer. what was edwin hubble's contribution to the field of astronomy? a. he discovered variable stars. b. he proved that the heliocentric model accurately described our solar system. c. he found a relationship between the period luminosity and distance of stars. d. he proved that the universe is finite. e. he discovered that the universe was expanding.