This is true, Darwin spent over 20 years developing his theory of natural selection
The medulla oblongata detects the levels of oxygen and carbon dioxide concentrations and signals the muscles in the heart, the lungs and diaphragm to increase or decrease thebreathing. The pons controls the speed of inhalation and exhalation orrespiration rate depending on the need of the body.
Answer is B. Porifera
Members of the phylum porifera includes animals which lack tissues. These animals are also called sponges. These are the simplest multicellular animals. Even though they are multicellular, they do not have any tissues or organs. They have cellular level of body organization. Sponges are aquatic animals and water plays a major role in the feeding, exchange of gases and as well as excretion.
