15. another name for the interstellar matter that will eventually form a star is a. supernova b. red giant c. black hole d. nebular 16. in the milky way, the most abundant gas in emission nebulae is a. helium b. hydrogen c. argon d. nitrogen 17. massive star terminate in a brilliant explosion called a a. red giant b. protostar c. neutron star d. supernova 18. all stars, regardless of size, eventually a. turn into black dwarfs b. explode c. run out of fuel and collapse d. become black holes 19. the sun is a a. black hole b. black dwarf c. main-sequence star d. red giant