Which of the following pairings of animal germ layer and derived tissue is incorrect?

The pairing of mesoderm and the nervous system is incorrect because the nervous system primarily develops from the ectoderm, not the mesoderm. The ectoderm is the outermost germ layer in embryonic development and gives rise to the nervous system through a process called neurulation, where a portion of the ectoderm forms the neural tube, which eventually differentiates into the brain and spinal cord.

In contrast, the endoderm is responsible for forming the inner linings of the digestive and respiratory tracts, which is why the pairing with the digestive tract is correct. The mesoderm does indeed give rise to muscle tissue, along with other structures such as bones and the cardiovascular system. The ectoderm's role in forming the outer covering of the organism further supports its classification in this context.