Mutualism, commensalism and parasitism
The correct solution for this is explained the first option. Since water has an equivalent amount or number of H ions and OH ions, pure water itself is not slightly acidic nor basic. This equality of ions, causes the pH of water to be around the mid point of the pH scale which goes from 0 - 14, and thus is 7. This is a neutral pH.
Arteries always flow away from the heart versus veins which carry blood to the heart. Bronchi are part of the lungs and move air. Platelets are components of blood that are responsible for clotting the blood.