According to Blackman's law of limiting factor, which of the following is the most important limting factor in the process of photosynthesis?

Options

A. Water
B. `CO_2`
C. Light
D. temperature

Answer

To solve the question regarding Blackman's law of limiting factor and its application to photosynthesis, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Blackman's Law of Limiting Factor**:
- Blackman proposed this law in 1905, stating that when a process is dependent on multiple factors, its rate is limited by the factor that is in the shortest supply. This means that if one factor is limited, it will restrict the overall rate of the process.

2. **Identify Factors Affecting Photosynthesis**:
- Photosynthesis is influenced by several factors including:
- Light intensity
- Carbon dioxide concentration
- Water availability
- Temperature
- Presence of chlorophyll

3. **Evaluate Each Option**:
- **Option 1: Water**: While water is essential for photosynthesis, it is not always the limiting factor. If water is abundant, it won't limit the process.
- **Option 2: Carbon Dioxide**: Similar to water, carbon dioxide is important, but it may not always be the limiting factor if other conditions are favorable.
- **Option 3: Light**: Light is often the most critical factor because photosynthesis relies heavily on light energy. If light intensity is low, it can significantly limit the rate of photosynthesis.
- **Option 4: Temperature**: Temperature affects the rate of photosynthesis, but it is not typically the most limiting factor compared to light.

4. **Conclusion**:
- Based on the evaluation, the most important limiting factor in the process of photosynthesis, according to Blackman's law, is **light**. Therefore, the correct answer is **Option 3: Light**.