The exchange of gases between the alveoli and capillaries of the lungs happens because of what?
the movement of substances from an area of high
concentration to an area of low concentration

the answer would be d

b. read the phase at the intersection of any given temperature and pressure.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products