The pair of ions having same electronic configuration is

Cr 24 =[Ar]3d5,4s1Cr 24 3+=[Ar]3d3Fe 26 =[Ar]3d6,4s2Fe 26 3+=[Ar]3d5Mn 25 =[Ar]3d5,4s2Mn 25 2+=[Ar]3d5Co 27 =[Ar]3d7,4s2Co 27 3+=[Ar]3d6Sc 21 =[Ar]3d1,4s2Sc 21 3+=[Ar]Thus, Fe3+ and Mn2+ have the same electronic configuration.