The embryo has three germ layers. The ectoderm, mesoderm, and endoderm. The endoderm is the innermost layer. Other than the endocrine glands, the other tissues that develop from the endoderm are the gastrointestinal tract, urinary and auditory system, and the respiratory tract.
The step that is an important part of the process by which ecology guides humans to a sustainable future is that behavior is changed after the cause of the problem is identified. The correct answer is D.
