What is the approximate age of universe according to Big-bang theory ?

Options

A. 137 million years
B. 137 billion years
C. 13.7 million years
D. 13.7 billion years

Explanation

**Step-by-Step Solution:**

1. **Understanding the Big Bang Theory**: The Big Bang Theory posits that the universe originated from an extremely hot and dense point. This event marks the beginning of the universe as we know it.

2. **Time Frame of the Big Bang**: According to this theory, the universe began to expand approximately 13 billion years ago.

3. **Refining the Estimate**: More precise measurements and calculations suggest that the age of the universe is about 13.7 billion years. This figure is derived from various astronomical observations and studies.

4. **Conclusion**: Therefore, according to the Big Bang Theory, the approximate age of the universe is around 13.7 billion years.

**Final Answer**: The approximate age of the universe according to the Big Bang Theory is 13.7 billion years.

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