Identify the reagents shown in bold in the following equations as nucleophiles or electrophiles.
(a) `CH_(3)COOH+OH^(-) rarr CH_(3)COO^(-)+H_(2)O`
(b) `CH_(3)COCH_(3)+NC^(-) rarr CH_(3)C(CN)OHCH_(3)`
(c) `C_(6)H_(6)+CH_(3)overset(+)(C)O rarr C_(6)H_(5)COCH_(3)`