In a star's cycle, which of the following can be thought of as opposites

Since there are no choices given, I will explain the cycle of a star. The beginning development of a star is marked by a supernova explosion, with the gases present in the nebula being forced to scatter. As the star shrinks, radiation of the surface increases and create pressure on the outside shell to push it away and forming a planetary nebula or white dwarf. The star is a ball of hot gases containing different kinds of elements at different cores. It has a very high temperature that radiates all throughout the Milky Way galaxy. The star has four main parts; the core, photosphere, chromospheres and corona. The outer core of a star located at the chromospheres contains mostly of hydrogen. Inside the hydrogen is helium then carbon, oxygen, neon, magnesium silicon and the inert gas. When a star releases energy it is due to the thermonuclear fusion of hydrogen into helium.