The seasonal activity of cambium is promoted by
(a) Proline
(b) Auxins
(c) Ethylene
(d) Abscissic acid

Options

A. Proline
B. Auxins
C. Ethylene
D. Abscissic acid

Answer

To determine which substance promotes the seasonal activity of cambium, we can analyze each option provided in the question.

1. **Understanding Cambium**: Cambium is a layer of tissue in plants responsible for secondary growth, which involves the formation of secondary xylem (wood) and secondary phloem (bark). This growth is crucial for the plant's ability to increase in girth.

2. **Analyzing the Options**:
- **(a) Proline**: Proline is an amino acid, not a phytohormone. While it plays a role in plant stress responses, it does not promote cambial activity.
- **(b) Auxins**: Auxins are a class of plant hormones that regulate various aspects of growth and development, including cell elongation and root formation. However, they are not specifically known for promoting cambial activity.
- **(c) Ethylene**: Ethylene is a gaseous plant hormone that plays a significant role in regulating growth and development. It is known to promote cambial activity, particularly in the context of secondary growth.
- **(d) Abscisic acid**: This hormone is primarily involved in stress responses and the regulation of stomatal closure. It does not promote cambial activity.

3. **Conclusion**: Based on the analysis, the hormone that promotes the seasonal activity of cambium is **(c) Ethylene**.

### Final Answer:
(c) Ethylene