Identify the vertebrate group of animals characterized by crop and gizzard in its digestive system. Osteichthyes, Amphibia, Reptilia, Aves

The digestive system of most of the aves consists of the pharynx, oesophagus, crop, proventriculus, gizzard, small intestine and large intestine. Proventriculus and gizzard are parts of the stomach. From the oesophagus, food passes into the crop. It then moves into the gizzard. Thus, the correct answer is option A.