Final answer:
During its early history, the universe indeed was dominated by matter, which is a true statement. The Big Bang led to the formation of various atomic particles and the large-scale structures we observe in the universe today. Dark and ordinary matter together accounted for the initial composition of the universe.
Step-by-step explanation:
The answer to the student's question about the early universe being dominated by matter is A) True. Astronomers estimate that all of the matter within the observable universe was concentrated in an extremely small volume 13.8 billion years ago, known as the Big Bang. During this hot and dense state, protons, neutrons, electrons, and neutrinos, and the nuclei of elements like deuterium, helium, and lithium were formed. Subsequently, when the universe was a few hundred thousand years old, it cooled down, matter ceased being a hot "soup," and began to clump together due to gravitational forces. This led to the formation of the large-scale structures we see today, such as galaxies and clusters.
The universe's initial composition was a mixture of ordinary visible matter, including all the elements, as well as dark matter, which interacts weakly with electromagnetic radiation and is detected through its gravitational effects. According to cosmic microwave background (CMB) measurements, the critical density of the universe is composed of about 31% matter (which includes dark matter) and 69% dark energy. The ordinary matter we are familiar with constitutes only about 5% of this critical density.