Each Successive Stage of Core Nuclear Reactions in a Massive

Each successive stage of core nuclear reactions in a massive star lasts for considerably less time than the previous stage (e.g.,for a 25-solar-mass star,carbon fusion lasts for 600 years,while neon fusion lasts for only 1 year) .One reason is that the:

A) later the stage of fusion, the less massive is the star.
B) later the stage of fusion, the more massive is the star.
C) more massive the nuclei, the fewer there are to react together.
D) more massive the nuclei, the less energy is released by fusing them together.