Question

The diagram below shows the life cycle of a "typical" star. In which stage will the star be characterized by nuclear reactions that produce all of the major elements on the periodic table up to iron?


A.
protostar
B.
interstellar cloud
C.
red giant
D.
main-sequence star

Answer 1

C. red giant

During the red‑giant (and later supergiant) phases the star undergoes helium burning and successive advanced burning stages (C, Ne, O, Si burning) at very high temperatures, producing the major elements up to iron. Protostars and interstellar clouds do not have sustained fusion, and main‑sequence stars primarily fuse hydrogen into helium.