Which one of the following is a batter nucleophile and why?

Explanation

`CH_(3)CH_(2)O^(-)` is a good nucleophile becauce the `-ve` charge is concentrated on one oxgyen only and the rate is directly proportional to the basicity.
(a) `CH_(3)COO^(-)` is a resonance hybrid of the following structures and the `-ve` charge is divided on the two carbon atoms.

(b) `C_(6)H_(5)O^(-)` is not a good nucleophile because the `-ve` charge is distributed at four positions.