Basically correct, as in, regardless of what was withheld during the year, the amount you owe should remain the same.
I don’t think scenario A exists - you are always going to have to pay taxes at the time of vesting, you don’t have the option to not pay at that time.
Also, not sure where you’re getting 24% from. Are you looking at the 24% for married filing jointly for 240k? Just fyi it is not a flat 24% of the total, that’s not how tax brackets work.
