I picked B, normally because I've rarely had cohorts travel exclusively with the party. Of the 3 characters in my games who have selected the leadership feat:
One was an Al-Quadim merchant rogue, his followers his business empire, and the cohort the guy who ran things while he adventured
Another owned a ship, the followers were the crew, and the cohort the 1st mate.
The last is a ruler of a small canton (domain) in oathbound, his followers are constables and law officials, and the cohort if his spymaster.
When they do travel with the party, the player controls a fair amount of their actions (and almost always in combat, since I have enough to keep track of), but the cohorts maintain their own identity.
Someone brought up the possibility of evil cohorts betraying the party, thats a possibility, but the cohort should be replaced with another soon afterwards. Though if you watch many popular movies, its more often than not the loyal #2 who is betrayed by the villain (unless the #2 is female).