The following are the statements about the effect of substrate concentration on the rate of enzymatic reactions.

a) With the increase in substrate concentration, the velocity of the enzymatic reaction rises first. 

b) The reaction ultimately reaches a maximum velocity (Vmax). 

c) With further rise in concentration of the substrate after reaching V_max, the rate of the reaction increases further. 

d) This is because there are a lot of free enzyme molecules left to bind with the additional substrate molecules.
Choose the correct options.