A star is said to be born when _____.
Apressure within a protostar becomes so great that a supernova occurs
Ba protostar reaches a temperature high enough for nuclear fusion to begin
Ca red giant collapses on itself and becomes a black hole
Da dark, cool interstellar cloud begins to contract
Apressure within a protostar becomes so great that a supernova occurs
Ba protostar reaches a temperature high enough for nuclear fusion to begin
Ca red giant collapses on itself and becomes a black hole
Da dark, cool interstellar cloud begins to contract