The standard electrode potential ( M ^ 3 + / M ^ 2 + ) for V, Cr,...

The ${E}^{⊝}$ values for the redox couple (${M}^{3 +} / {M}^{2 +}$) shows that ${Mn}^{2 +}$ and ${Co}^{2 +}$ ions are the strongest oxidising agents in aqueous solution.

The ions ${Ti}^{2 +}, {V}^{2 +}and{Cr}^{2 +}$ are strong reducing agents and will liberate hydrogen from a dilute acid.

So, the Correct answer is ${V}^{2 +}and{Cr}^{2 +}$.