Enzymatic activity is inhibited by which of the following?

The figure given shows the conversion of substrate into product by an enzyme. In which one of the four options,the components of the reaction labelled $a, b, c, \& \ d$ are identified correctly?
$(i)$ Potential energy
(ii) Transition state
(iii) Activation energy with enzyme
(iv) Activation energy without enzyme

The transition state structure of the substrate formed during an enzymatic reaction is:

Which of the following statements is not correct?

Chemically,enzymes are ....

Which enzyme is responsible for the hydrolysis of lactose?