Which of the following pairs is mismatched? Select one: a. endoderm - bone b. mesoderm - muscle c. ectoderm - skin d. neuroectoderm - nervous system e. neural crest cells - peripheral nervous system, skin pigment, tissues of the face

Answer: a. endoderm-bone

Explanation: In the context of embryonic development, bone tissue may arise from several precursor cell populations, such as the neural crest (some facial bones), lateral mesoderm (bones of the limbs, among others), and paraxial mesoderm (vertebrae and part of the skull). There is no evidence to suggest that any of the bony structures is derived from the endoderm germ layer.