Right answer is (a) True
Easy explanation: Within the micro-environment, the same bulk concentration may give two different stable concentrations which are follows:
A low concentration which gives faster rate of reaction, with no substrate inhibition and equally fast rate of inward diffusion sue to steep concentration gradient.
A high concentration which gives slower rate of reaction due to substrate inhibition and equally slow rate of inward diffusion due to concentration gradient going downward.
There is a possibility of an existence of a third intermediate concentration depicting an unstable state which is not naturally established and is of no practical consequence.