Once Carbon Begins Burning in the Core of a High-Mass

Once carbon begins burning in the core of a high-mass star,the outer layers begin to fall inward,driving up the fusion rates and speeding up the star's evolution primarily because:

A) the number of particles in the core is decreasing, which now take up less space.
B) most of the energy is now carried away from the core by escaping neutrinos, which have few if any obstacles to leaving the star.
C) carbon is a more stable element that appears to settle the star.
D) the light given off by the fusion of carbon is a different wavelength than that given off by previous reactions, so the radiation pressure is much smaller.