For an enzyme to effectively change its activity in response to a change in substrate concentration, it is most favorable for:

a) km to be less than cellular substrate concentrations.
b) km to be equal to cellular substrate concentrations.
c) km to be greater than cellular substrate concentrations.
d) vmax to be at the diffusion limit.
e) the substrate to also be an allosteric effector.

The substrate to also be an allosteric effector.

Explanation:

Inositol hexaphosphate (IHP) is an example of an allosteric effector, which are known substances that bind to the site of an enzyme, that are allosteric in nature, thereby leading to a corresponding increase or decrease in the activities of the enzyme.  These effectors can cause a change in the configuration of the enzymes by binding to a non-active site.

A positive allosteric effect do cause an increase in the activities of the enzyme while the negative allosteric effect causes the decrease in the activities of the enzymes.

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

to this one it would be receptive field