Biosynthesis of cytokinin takes place via

Options

A. Mevalonic acid cycle
B. Citric acid cycle
C. Calvin cycle
D. `C_(4)` cycle.

Answer

**Step-by-Step Solution:**

1. **Understanding Cytokinins**: Cytokinins are a class of plant hormones that play a crucial role in cell division, growth, and delaying leaf senescence.

2. **Identifying the Biosynthesis Pathway**: The question asks about the biosynthesis of cytokinins. To answer this, we need to identify the pathway through which cytokinins are synthesized in plants.

3. **Evaluating the Options**:
- **Option 1: Mavalonic Acid Cycle**: This is a pathway involved in the synthesis of various compounds, including cytokinins. It is known to produce isoprenoid compounds, which are precursors for cytokinin biosynthesis.
- **Option 2: Citric Acid Cycle**: This cycle is primarily involved in energy production and does not play a direct role in hormone synthesis. Therefore, it is not the correct answer.
- **Option 3: Calvin Cycle**: This cycle is part of photosynthesis and is not related to the synthesis of cytokinins. Hence, it is also incorrect.
- **Option 4: C4 Cycle**: This is another photosynthetic pathway and does not relate to hormone biosynthesis. Thus, it is not the correct answer.

4. **Conclusion**: After evaluating all the options, the correct answer is that the biosynthesis of cytokinins takes place via the Mavalonic Acid Cycle.

**Final Answer**: The biosynthesis of cytokinin takes place via the Mavalonic Acid Cycle.

---