An Interesting Finding About In-Group Mobility and Status Variations to Emerge

An interesting finding about in-group mobility and status variations to emerge from Jenkot's research is

A) once a particular status is achieved within the group, it is next to impossible for one to change it.
B) it is quite common and easy for lower status persons to fill high status positions.
C) persons who occupy high status positions are permitted to work at lower status jobs if they so choose.
D) there are no strict status distinctions or ranks with such groups; everyone pitches in to do whatever may be called for at a given time without regard to previous roles.