The primary purpose of a Community of Practice (CoP) in the Disciplined Agile (DA) framework is to share knowledge among a group of like-minded people. CoPs bring together people who share a common interest or practice, enabling them to exchange insights, experiences, and best practices to enhance their collective expertise. Options B (bringing all the experts together) and D (mentoring, coaching, and guiding others) are secondary benefits but not the primary purpose. Option C (selling a competency) does not align with the purpose of a CoP.