A

To solve the vector equations according to the given vector diagrams:
1. **For Column-I (i)**, the vector diagram indicates that $\vec{a} = \vec{b} + \vec{c}$, which matches with **Column-II [A]**.
2. **For Column-I (ii)**, we identify it as $\vec{b} - \vec{c} = \vec{a}$, which corresponds to **Column-II [B]**.
3. **For Column-I (iii)**, it represents $\vec{a} + \vec{b} = -\vec{c}$, matching with **Column-II [C]**.
4. **For Column-I (iv)**, we see that it demonstrates $\vec{a} + \vec{b} = \vec{c}$, aligning with **Column-II [D]**.
Thus, the matching is: (i)→[A], (ii)→[B], (iii)→[C], (iv)→[D]. Therefore, the correct option is A.