Correct order of oxidising nature is

Which one of these is not known?

Which of the following statements are correct?
$A$. The $M^{3+}/M^{2+}$ reduction potential for iron is greater than manganese.
$B$. The higher oxidation states of first row $d$-block elements get stabilized by oxide ion.
$C$. Aqueous solution of $Cr^{2+}$ can liberate hydrogen from dilute acid.
$D$. Magnetic moment of $V^{2+}$ is observed between $4.4-5.2 \ BM$.
Choose the correct answer from the options given below:

Which pair of compounds contains both metals in their highest possible oxidation state?

Which of the following are basic oxides among $Mn_2O_7 (I)$,$V_2O_3 (II)$,$V_2O_5 (III)$,$CrO (IV)$,and $Cr_2O_3 (V)$?

Among $K, Ca, Fe,$ and $Zn$,the element which can form more than one binary compound with chlorine is