Photosynthetic efficiency is represented by
`X/("Incident total solar radiation.")`
The X ' in this equation represents

Options

A. Gross primary productivity
B. Net primary productivity
C. Secondary productivity
D. None of these

Answer

To solve the question regarding what 'X' represents in the equation for photosynthetic efficiency, we can break down the problem step by step:

### Step-by-Step Solution:

1. **Understanding Photosynthetic Efficiency**:
- Photosynthetic efficiency is a measure of how effectively plants convert solar energy into chemical energy through the process of photosynthesis. It is expressed as a ratio of the amount of energy captured by photosynthesis to the total solar energy incident on the plant.

2. **Defining the Variables**:
- In the equation given, `X / (Incident total solar radiation)`, 'X' represents the amount of energy produced through photosynthesis.

3. **Identifying 'X'**:
- The energy produced through photosynthesis can be quantified as Gross Primary Productivity (GPP). GPP is the total amount of organic matter or energy produced by photosynthetic organisms in a given area and time.

4. **Conclusion**:
- Therefore, in the context of the equation, 'X' represents Gross Primary Productivity (GPP), which is the total rate of photosynthesis occurring in that environment.

### Final Answer:
- The 'X' in the equation represents **Gross Primary Productivity (GPP)**.