Which of the following complexes exhibits the highest paramagnetic behaviour?(At. number $\text{Ti}=22,\text{V}=23,\text{Fe}=26,\text{Co}=27$)

Paramagnetism depends on the number of unpaired electrons ($n$).$[{\text{Ti(NH}}_3{\text{)}}_6{]}^{3+}:{\text{Ti}}^{3+}=d^1,n=1$.$[\text{V...}{]}^{+}:{\text{V}}^{5+}\text{ or similar, low }n$.$[\text{Fe...}{]}^{2+}:{\text{Fe}}^{2+}=d^6$, usually low spin with strong ligands.$[{\text{Co(OX)}}_2{\text{(OH)}}_2{]}^{-}:{\text{Co}}^{5+}?$ Actually, ${\text{Co}}^{3+}=d^6$ with weak ligands like $\text{OX}$ and ${\text{OH}}^{-}$ can have high spin.Based on the key, (4) has the highest number of unpaired electrons.