Step 1: Understanding the Concept
Ligands can be anionic, neutral or cationic depending on their charge.
Step 2: Check each ligand
Isothiocyanato is \(\text{NCS}^-\), which is negatively charged.
Ammine is \(\text{NH}_3\), aqua is \(\text{H}_2\text{O}\) and ethylenediamine is \(\text{H}_2\text{N-CH}_2\text{-CH}_2\text{-NH}_2\), all neutral.
Step 3: Conclude
Isothiocyanato is the anionic ligand.
Final Answer:
Isothiocyanato is the anionic ligand.
\[ \boxed{\text{(A) }\text{Isothiocyanato}} \]