Who said that organisms develop from existing organisms

Options

A. Aristotle
B. Louis Pasteur
C. Oparin
D. Morgan

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks who proposed that organisms develop from existing organisms. This concept is fundamental in biology and relates to the origins of life.

2. **Identifying the Options**: The options provided are:
- A) Aristotle
- B) Louis Pasteur
- C) Operon
- D) Morgan

3. **Analyzing Each Option**:
- **Aristotle**: While Aristotle made significant contributions to various fields, he did not specifically propose that life arises from existing life. His ideas on spontaneous generation were later disproven.
- **Louis Pasteur**: Pasteur is known for his work in microbiology and for proposing the theory of biogenesis, which states that life comes from pre-existing life. This aligns with the question.
- **Operon**: This term refers to a group of genes that are regulated together, not a theory about the origin of life.
- **Morgan**: Thomas Hunt Morgan is known for his work in genetics, particularly regarding chromosomes and heredity, but he did not address the origin of life in the context of existing organisms.

4. **Conclusion**: Based on the analysis, the correct answer is **B) Louis Pasteur**, as he proposed the theory of biogenesis, which states that organisms develop from existing organisms.