Which statement is most correct about the Value Stream Map in Figure $1?$

Figure $1$:

Select one:

a$.$ The focus for improvement should be Operation $C$ because it has the longest Cycle Time $(\frac{C}{T})$

b$.$ The focus for improvement should be Operation $C$ because it has the longest change Over Time $(\frac{C}{O})$ and the longest Cycle Time $($C$/$T$)$ and lowest uptime