Final answer:
Paul McCartney was the Beatles member most keen on keeping the band together in the late 1960s, organizing meetings and planning projects to maintain the group's cohesion. The correct option is B. Paul McCartney.
Step-by-step explanation:
The member of The Beatles who was most interested in keeping the band together in the late 1960s was Paul McCartney. McCartney was the one who pushed for business meetings and consultations with management to keep the band's affairs in order, even as personal and creative differences arose between the members.
While John Lennon, George Harrison, and Ringo Starr all showed varying degrees of interest in moving on to other projects, McCartney was often the one trying to organize the group and plan future projects such as the album Let It Be and the film project that became the documentary of the same name.
The correct option is B. Paul McCartney.