Given below are two statements.

Statement I : In cockroaches, the gizzard has an outer layer of thick circular muscles.

Statement II : Gizzard also has an inner cuticle forming six highly chitinous plates called mandibles.

In light of the given statements, choose the correct answer from the options given below.

Statement I is correct but statement II is incorrect.

Statement I is correct. In cockroaches, the gizzard does indeed have an outer layer of thick circular muscles. These muscles play a crucial role in grinding and breaking down food particles during the process of digestion. So, this statement is correct.

Statement II is incorrect. The gizzard in cockroaches has  an inner cuticle forming chitinous plates called teeth. Mandibles are actually paired appendages found in the mouthparts of insects, including cockroaches, which are used for biting and chewing food. The gizzard itself does not have this structure.