$KCNS$ can identify the following basic radicals:
A. $C{{u}^{2+}}$
B. $C{{o}^{2+}}$
C. $F{{e}^{3+}}$
D. All of the above

Hint: As we know that a radical is a molecule that has one unpaired electron, it is basically a valence shell. The basic radicals that are positively charged are called basic radicals. KCNS is called potassium thiocyanate.

Complete step by step answer:
- KCNS is found to identify all the three basic radicals that are: $C{{u}^{2+}}$ ,$C{{o}^{2+}}$ and $F{{e}^{3+}}$.
- It is found that when Fe(III) ion is reacted with thiocyanate ions, then a blood red colouration takes place. We can see the reaction that takes place during this:
\[FeC{{l}_{3}}+3KSCN\to Fe{{(SCN)}_{3}}+3KCl\]
- It is found that when Cu(II) ion is reacted with thiocyanate ions, then a black red colouration takes place. We can see the reaction that takes place during this:
\[Cu+2KCNS\to Cu{{\left( CNS \right)}_{2}}+2K\]
- It is found that when Co(II) ions are reacted with potassium thiocyanate ions, then there is a formation of blue coloured potassium cobalt thiocyanate. We can see the reaction that takes place during this:
\[CoC{{l}_{2}}+4KCNS\to {{(K)}_{2}}\left[ Co{{\left( CNS \right)}_{4}} \right]+2KCl\]

Hence, we can conclude that the correct option is (d), that is KCNS can identify all the given basic radicals that are ,$C{{u}^{2+}}$ ,$C{{o}^{2+}}$ and $F{{e}^{3+}}$.

Note: We should not get confused in between the terms acidic and basic radicals. The basic radicals are those that react and combine only with acidic radicals to form a compound. Whereas, acidic radicals react and combine only with basic radicals to form a compound.