What legs can you charge someone as a Commercial Pilot?

Hello Everyone,

I have my commercial checkride coming up and I had one question that I can’t seem to find the answer to. A scenario I was presented with was asking which leg can you charge someone if you fly from Airport A to Airport B to pick them up (where they live) on the way to Airport C (final destination). Assuming they are providing the airplane this scenario should be legal and I can accept compensation but what legs can I charge for is my question. My instinct is to say for all legs because I am only charging for my pilot services and not for transportation of people.

Also the same scenario but now let’s say I am providing the aircraft but I am just using my private pilot privileges and asking for pro rata share with friends. What legs can I charge the pro rata share on?