Final answer:
The early universe's matter that formed galaxies and stars primarily consisted of hydrogen and helium at an approximately 3:1 ratio. Lighter elements like lithium were present in much smaller amounts. Heavier elements were later produced inside stars. The correct option is B.
Step-by-step explanation:
The matter in the early universe that eventually condensed into galaxies and then into stars consisted mainly of hydrogen and helium. These were the two simplest elements, along with a tiny amount of lithium, formed in appreciable abundances at the beginning of the universe.
The early universe remained hot enough for fusion for only a brief period, which led to the formation of these light elements. The heavier elements formed later inside stars, which are essentially large masses of hydrogen gas undergoing fusion reactions at their dense cores. Stars create energy by fusing hydrogen into helium, and in larger stars, heavier elements are produced.
Based on the early composition and models of our universe, it's understood that hydrogen and helium were present in an approximately 3:1 ratio. This abundance of hydrogen and helium set the stage for the formation of the first stars that later contributed to the chemical diversity of the universe by fusing lighter elements into heavier ones.