Photosynthetically active radiation (PAR) represents the following range of wavelength
(a) 400-700 nm
(b) 450-920 nm
(c) 340-450 nm
(d) 500-600 nm

Options

A. 400-700 nm
B. 450-920 nm
C. 340-450 nm
D. 500-600 nm

Answer

To solve the question regarding the range of wavelengths for Photosynthetically Active Radiation (PAR), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of PAR**:
- Photosynthetically Active Radiation (PAR) refers to the portion of the light spectrum that plants can use for photosynthesis. It is essential for plant growth and energy production.

2. **Identify the Wavelength Range**:
- The question provides four options for the wavelength range of PAR. We need to identify which of these ranges is correct based on scientific knowledge.

3. **Review the Options**:
- Option (a): 400-700 nm
- Option (b): 450-920 nm
- Option (c): 340-450 nm
- Option (d): 500-600 nm

4. **Recall the Definition of PAR**:
- PAR is defined as the range of light wavelengths that are usable by plants for photosynthesis. This range is typically accepted to be from 400 nm to 700 nm, which includes the visible light spectrum.

5. **Evaluate Each Option**:
- Option (a) 400-700 nm: This matches the accepted definition of PAR.
- Option (b) 450-920 nm: This range extends beyond the typical PAR range.
- Option (c) 340-450 nm: This range is too low and does not include the full spectrum of PAR.
- Option (d) 500-600 nm: This range is too narrow and does not encompass the entire PAR spectrum.

6. **Select the Correct Answer**:
- Based on the evaluation, the correct answer is **Option (a) 400-700 nm**.

### Final Answer:
The correct range of wavelengths for Photosynthetically Active Radiation (PAR) is **(a) 400-700 nm**.

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