Why people are suggested to work with one headhunter?

A．If you are submitted by more than one firm, there is a chance that the two headhunters will get into a tug-of-war, arguing with the client company over who should be allowed to represent you.
B．If you’re working with a recruiter and a similar role comes up that matches your job preferences, they may submit you and let you know afterwards.
C．One problem that can arise when working with multiple recruiters is overlap with candidates, especially when the talent pool is limited, such as for a niche.
D．All of the above.