The activity of cambium is under the control of -

Options

A. Many physiological factors
B. Many environmental factors
C. both
D. Only photoperiod

Answer

To answer the question regarding the control of cambium activity, we can break down the information as follows:

### Step-by-Step Solution:

1. **Understanding Cambium**:
- Cambium is a layer of tissue in plants that is responsible for secondary growth, which increases the thickness of stems and roots.

2. **Factors Influencing Cambium Activity**:
- Cambium activity is influenced by various factors. These can be physiological (internal factors) and environmental (external factors).

3. **Physiological Factors**:
- These include hormones such as auxins, gibberellins, and cytokinins, which play significant roles in cell division and growth.

4. **Environmental Factors**:
- Environmental factors include light, temperature, water availability, and soil nutrients. For instance, photoperiod (the duration of light and dark periods) can significantly influence cambium activity.

5. **Conclusion**:
- Based on the above points, we can conclude that the activity of cambium is under the control of both physiological and environmental factors.

### Final Answer:
The activity of cambium is under the control of both physiological and environmental factors.

---