Magnesium/Manganese is the major component of ring structure of chlorophyll.

Explanation

**Step-by-Step Solution:**

1. **Understanding Chlorophyll Structure**: Chlorophyll is a pigment found in plants that is essential for photosynthesis. It has a unique structure that includes a porphyrin ring.

2. **Identifying Key Components**: The porphyrin ring of chlorophyll contains a central metal ion. In the case of chlorophyll, this metal ion is magnesium (Mg).

3. **Role of Magnesium**: Magnesium is classified as a macronutrient, meaning it is required in larger quantities by plants. It is absorbed from the soil in the form of divalent magnesium ions (Mg²⁺).

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