Which theory argument that life on earth came from outer space ?

Options

A. Theory of panspermia
B. Cosmozoic theory
C. Spore theory
D. All of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which theory suggests that life on Earth originated from outer space.

2. **Identifying Relevant Theories**: There are several theories regarding the origin of life, including the theory of spontaneous generation, extraterrestrial theories, and theories related to space.

3. **Focusing on Extraterrestrial Theories**: Among these, the extraterrestrial theories specifically address the idea that life may have originated from outside Earth.

4. **Introducing Panspermia**: One of the key theories that supports the idea of life coming from outer space is the **Panspermia theory**. This theory posits that life, or at least the building blocks of life, were brought to Earth from other planets or celestial bodies.

5. **Explaining Panspermia**: Panspermia suggests that microscopic life forms, such as spores, could survive the harsh conditions of space and travel between planets. These spores could then land on Earth and develop into new life forms.

6. **Mentioning Variants of Panspermia**: Within the Panspermia theory, there are variations such as the **Cosmozoic theory**, which refers to the spores as "Cosmozoa". This reinforces the idea that life could have originated from extraterrestrial sources.

7. **Conclusion**: Therefore, the theory that argues that life on Earth came from outer space is primarily the **Panspermia theory**, along with its variants like the Cosmozoic theory.

**Final Answer**: The theory that argues that life on Earth came from outer space is the **Panspermia theory**.

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