NUCLEOPHILICITY..

is it (b) ?

it is b
NH₂ is a strong nucleophile while OH^- is a poor nucleophile

YA ..

ans is (b)

But I don"t remember the basic thing behind nucleophilicity order..

CAN ANYONE PLZ EXPLAIN THE REASON FOR THIS ORDER...

Nucleophilicity is the ability of an atom to donate an electron. Basicity is the ability of an atom to abstract a proton. Nitrogen being less electronegative than Oxygen, can donate an electron. So it has high nucloephilicity.

Nucleophilicity is the ability of an electron-rich atom to attack a positively(partially or fully) charged carbon. It is measured by the reaction's rate constant. Basicity is the atom's ability to abstract a proton. It is measured in terms of equilibrium constant K_b.

B B B B B B B B

As the electronegativity increases, nucleophilicity decreases.
So, OH- < NH2-

CH3COO- is a stable anion , hence it is least nucleophilic .