Among the following the strongest nucleophile is
A) Nucleophiles are those substances which can donate a pair of electrons. These can be neutral or negative. The nucleophilic power depends on the tendency of species to donate electron. This is more, when an electron pushing group (+I group) is present. Among the alkyl groups, those having higher number of C-atoms will push more, hence ethyl I> methyl.
C2H5↠(+I)CH5+CH2(−I)S−H, CH3↠(+I)O||C−O−,CH3↠(+I) NH2