Respuesta :
Answer: B. red giant stage
When the sun runs out of fuel-hydrogen, its atmosphere expands and it becomes a red-giant star. The Sun would leave the main-sequence stage and enter the red-giant stage in which huge pressure generated in its core pushes the atmosphere outwards making it expand and nuclear fusion reaction of heavier nuclei starts. The end stage of Sun would be formation of a white dwarf.
Thus, from the given options, correct answer is B. red giant stage
