Final answer:
The age of the universe is approximately 13.8 billion years. This estimate is based on the expansion of the universe and is supported by the age of astronomical objects. The correct answer is d. 13.8 billion years.
Step-by-step explanation:
The age of the universe is approximately 13.8 billion years (13.799 ± 0.038 billion years).
This estimate is based on the expansion of the universe, which astronomers have traced backward in time.
The uncertainty in the age of the universe is about 38 million years.
The age of the universe is determined by measuring the Hubble constant, which is the rate of the universe's expansion, as well as the fraction of dark energy and matter in the universe.
Comparing the age of the universe to the age of astronomical objects, it is found that some of the globular-cluster stars in the Milky Way must have formed less than a billion years after the expansion began, indicating that the universe is indeed older than a billion years.
The age of the universe is much greater than the other options provided. The correct answer is d. 13.8 billion years.