~Which shows the correct order of processes leading up to the formation of a main sequence star?~

A. Gases condense to form a nebula, gravity causes the nebula to collapse and spin, nuclear fusion occurs, and a protostar forms.
B. A protostar forms, nuclear fusion occurs, gases condense to form a nebula, and gravity causes the nebula to collapse and spin.
C. Gases condense to form a nebula, gravity causes the nebula to collapse and spin, protostar forms, and nuclear fusion occurs.
D. A protostar forms, gases condense to form a nebula, gravity causes the nebula to collapse and spin, and nuclear fusion occurs.