Which one of the following statements is true regarding enzymes?

The ratio of the enzyme to substrate molecule can be as high as

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

Who discovered the allosteric inhibition of enzymes?

What is released from the active site of an enzyme at the end of the reaction?

How is a substrate converted into a product?