Answer:
Endoderm
Explanation:
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.
Have a developmentally more mature understanding of death
Answer: it produced oxygen as a waste product
Explanation: there was more free oxygen
Id say C. It makes the most sense to me.