Explain the following findings.
(a) One full equivalent of base must be used in the Claisen or Dieckmann condensation.
(b) Ethyl acetate readily undergoes a Claisen condensation in the presence of one equivalent of sodium ethoxide, but phenyl acetate does not undergo a Claisen condensation in the presence of one equivalent of sodium phenoxide.
(c) Although the aldol condensation can be catalyzed by acid, the Claisen condensation cannot.