friend (who does not have the new awareness which you have gained from this course) suggests that the mechanism that keeps the Sun shining as brightly as it does is the burning of coal. You brilliantly challenge his theory! Your challenge comes in several related steps; which of the following is one of those steps? a. we have found many more neutrinos than we expected in our underground experiments b. new protostars shine by gravitational collapse (the heat of clumping) c. the dating of radioactive rocks show that the Earth and thus the Sun are billions of years old d. most of the Sun is made of antimatter (which explodes when it touches matter) e. the C-N-O cycle can also produce helium