Explanation:

Fe(EDTA) Complex:
- The complex [Fe(EDTA)]- consists of a central iron (Fe) atom coordinated to six ligands of ethylenediaminetetraacetate (EDTA).
- Each EDTA ligand binds to the iron atom through four oxygen atoms and two nitrogen atoms, forming a chelate ring.

Optical Isomerism:
- Optical isomerism, also known as chirality, occurs when a compound has a non-superimposable mirror image.
- This property arises when a molecule contains a chiral center, which is an atom bonded to four different groups.

Chelate Rings:
- In the Fe(EDTA) complex, each EDTA ligand forms a chelate ring with the central iron atom.
- A chelate ring is a cyclic structure formed when a ligand binds to a metal atom through multiple atoms or groups.
- In this case, the EDTA ligand forms a six-membered chelate ring with the iron atom.

Counting the Rings:
- To determine the number of rings formed in the Fe(EDTA) complex, we need to count the chelate rings formed by each EDTA ligand.
- Since there are six EDTA ligands in the complex, we need to count the number of chelate rings formed by each ligand.

Counting Chelate Rings per Ligand:
- Each EDTA ligand forms one chelate ring with the central iron atom.
- Therefore, the number of chelate rings formed per ligand is 1.

Total Number of Rings:
- Since there are six EDTA ligands in the complex and each ligand forms one chelate ring, the total number of rings formed in the Fe(EDTA) complex is 6.

Correct Answer:
- The correct answer is '6', not '5'.