`S_(1) : Mn^(2+)` compounds more stable than `Fe^(2+)` towards oxidation to their `+3` state.
`S_(2)` : Titanium and copper both in the first series of transition metals exhibits `+1` oxidation state most frequently.
`S_(3) : Cu^(+)` ions is stable in aqueous solutions.
`S_(4)` : The `E^(0)` value for the `Mn^(3+)//Mn^(2+)` couple much more positive than that for `Cr^(3+)//Cr^(2+)` or `Fe^(3+)//Fe^(2+)`,

Answer

B

Explanation

`S_1`:It is because `Mn^(2+)` has `3d^5` configuration which has extra stability.
`S_2:`Not titanium but Copper , because with +1 oxidation state an extra stable configuration ,`3d^10` results.
`S_3`:Not stable as it undergoes disproportionation `2Cu^(+)(aq)toCu^(2+)(aq)+Cu(s)`.The `E^@` value for this is favourable.