Why Must the Sun's Rate of Fusion Gradually Rise Over

Multiple Choice

Why must the Sun's rate of fusion gradually rise over billions of years?

A) The Sun becomes less efficient and must increase the rate of fusion to produce the same amount of energy.
B) Fusion reactions decrease the overall number of particles in the core,causing the core to shrink,converting gravitational potential energy into thermal energy,and increasing the rate of fusion.
C) The radiation produced by fusion reactions that is trapped in the core gradually raises the temperature,increasing the rate of fusion.
D) The Sun gets heavier as it gets older,and the stronger inward pull of gravity increases the fusion rate.
E) The rate of fusion is not rising;it is actually decreasing over time.