Two pigment system theory of photosynthesis was proposed by or Conept of evidence for existence two photosystem is photosynthesis was given by

Options

A. Hill
B. Blackman
C. Emerson
D. Arnon.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the two pigment system theory of photosynthesis and who proposed it, as well as the evidence for the existence of two photosystems in photosynthesis.

2. **Identifying the Key Concepts**:
- The two pigment system theory refers to the presence of two different photosystems in the process of photosynthesis.
- These photosystems are known as Photosystem I (PSI) and Photosystem II (PSII).
- The concept of the Emerson effect is crucial in understanding the evidence for these two photosystems.

3. **Explaining the Emerson Effect**:
- The Emerson effect describes the phenomenon where the rate of photosynthesis increases significantly when plants are exposed to two specific wavelengths of light: 670 nm (red light) and 700 nm (far-red light).
- When both wavelengths are present simultaneously, the rate of photosynthesis is higher than the sum of the rates when each wavelength is presented alone.

4. **Linking Evidence to the Theory**:
- The Emerson effect serves as evidence for the existence of two distinct photosystems that work together in photosynthesis.
- This effect was observed by the scientist named Emerson, which is why it is named after him.

5. **Conclusion**: Therefore, the two pigment system theory of photosynthesis was proposed by Emerson, and the evidence for the existence of the two photosystems is also attributed to his work.

### Final Answer:
The two pigment system theory of photosynthesis was proposed by Emerson.