Which of the following are thought to be mechanisms that can cause a giant molecular cloud to collapse and form a protostar? A. The shockwave from a nearby supernova B. The shockwave from a newly formed high-mass star that is nearby C. A planetary nebula floating past D. The shockwave experienced by the cloud as it passes through a spiral arm E. Mergers of spiral galaxies.

All the above

Explanation:

The stellar evolution is processed by which the star changes its course in the time and this depends on the mss of the star and can range of a million to trillion years and all starts are formed by the collapse of the molecular nebula of dust and the gases and settle down as the protostars and in the process of the main sequence of the stars. The shockwaves from the supernova and the newly formed star and planetary nebula that is floating in the past and the shows waves that experience the cloud as it passes through the spiral arms and merger of the galaxies.

The answer would be political systems .