Deep in the core of the Sun, 620 million metric tons of hydrogen nuclei are converted into 616 million metric tons
of helium nuclei every second. What happens to the
"missing mass” in the Sun's core?

Select one:

A. The "missing mass" is converted to heat during an exothermic
chemical reaction that produces a new chemical species.

B. The "missing mass" is transformed into energy in a fission
reaction

C. The "missing mass” is converted to heat during an
endothermic chemical reaction that produces a new chemical
species

D. The "missing mass” is transformed into energy in a fusion
reaction