Which of the following carbonyl compound / amine pairs give an ENAMINE as the isolable condensation product (with acid catalysis and water removal)?

An enamine needs a secondary amine and a carbonyl compound with an alpha hydrogen to lose after iminium formation. Cyclohexanone + pyrrolidine and propanal + piperidine fit. Cyclohexylamine is a primary amine and gives an imine. Benzaldehyde has no alpha hydrogen, so it cannot give an enamine with pyrrolidine.