Substituents on an aromatic ring can have several effects on electrophilic aromatic substitution reactions. Substituents can activate or deactivate the ring to substitution, donate or withdraw electrons inductively, donate or withdraw electrons through resonance, and direct substitution either to the ortho/para or to the meta positions. From the following lists, select the substituents that have the indicated property. The substituents are written as -XY, where X is the atom directly bound to the aromatic ring.

a. Br-OCOCH3-COOH-NHCOCH3Withdrawal of electrons through resonance.
b. OCH3-SO3H-OH-NO2Ortho/para-directed substitution.
c. Cl-NHCOCH3-CN-CH3-COOH