Final answer:
Betelgeuse, being a high mass star with a core of hydrogen and helium, is currently engaging in hydrogen fusion, which converts hydrogen into helium. This corresponds to option C and is a typical stage in the life cycle of a massive star.
Step-by-step explanation:
The star Betelgeuse is a high mass star with a core composed of hydrogen and helium. Since it is a high mass star, it initially undergoes hydrogen fusion in its core, where hydrogen is fused to form helium. This stage of stellar evolution aligns with option C, which refers to a star that is currently fusing hydrogen to form helium in its core. As the star evolves, helium accumulation in the core will raise the temperature and density, eventually leading to helium fusion, where helium fuses into heavier elements like carbon and oxygen, which corresponds to option D. However, since the question specifically states that Betelgeuse's core is composed of hydrogen and helium, it is undergoing hydrogen fusion.