According to the current cosmological model, the age of the universe is about:

• A. 4.5 billion years
• B. 13.7 billion years
• C. 9.8 billion years
• D. 20 billion years

Answer: (B)

The age of the universe is determined by the history of cosmic expansion. Using the standard cosmological model (Lambda-CDM) and observations like the cosmic microwave background, distant supernovae, and the large-scale structure, scientists backtrack how the universe has expanded from a hot, dense origin to today. When you work through that expansion history with current parameters, the result is about 13.7 to 13.8 billion years. That’s why this option is the best match to the data. The other numbers don’t fit the measurements: 4.5 billion years is the age of the Earth, not the universe; 9.8 billion is too young given the observed expansion history; 20 billion is older than what the data support.