Massive Stars Explode Soon After Fusion to Iron Begins Because

Massive stars explode soon after fusion to iron begins because

A) iron has the smallest binding energy of all elements.
B) neutrinos emitted during the fusion to iron are captured by the star's lighter elements.
C) fusion of elements heavier than iron requires energy, so the star runs out of fuel and cannot hold itself up against gravity.
D) stars do not contain elements heavier than iron; these are made in supernovae explosions.
E) iron nuclei are unstable and rapidly break apart into lighter elements.