The graph illustrates how substrate concentration affects an enzyme-catalysed reaction both in the presence and in the absence of a competitive inhibitor. What is the effect of the competitive inhibitor on $V_{\max}$ and $K_m$?
- A$V_{\max}$ decreases and $K_m$ decreases.
- B$V_{\max}$ stays the same and $K_m$ decreases.
- C$V_{\max}$ stays the same and $K_m$ increases.
- D$V_{\max}$ decreases and $K_m$ stays the same.