Which of the following is the most abundant element in the universe?

This question tests knowledge of basic astrophysics and the composition of the universe. The abundance of elements is a key concept in understanding stellar formation and the origins of matter.

• Hydrogen (A) is by far the most abundant element in the universe, constituting approximately 75% of its elemental mass. It is the primary fuel for stars through nuclear fusion.
• Helium (C) is the second most abundant element, making up about 24% of the universe's elemental mass.
• Oxygen (D) and Carbon (B) are significantly less abundant, formed primarily in the cores of stars through stellar nucleosynthesis.