1. Air enters the nostrils.
2. Air passes from the trachea to the bronchi
3. Air diffuses from the alveoli to the blood cells.
4. Oxygen enters the blood cells.
5. Blood transports oxygen to other cells.
I am pretty sure the answer is D (combination)
Chemical bond is the right awnser
Answer:
Although more offsprings are produced by the process of external fertilization but the process of internal fertilization is more efficient as compared to external fertilization. This is because, in external fertilization, it is more difficult for the sperm to find the egg and fertilize it. Even after fertilization, it might be that the zygote gets eaten up by a predator. There are none such risks in internal fertilization. The zygote is protected during the internal fertilization which makes this process more efficient.