In which mobile device policy are all devices strictly for business use without personal activities allowed?

The correct choice, which indicates that all devices are strictly for business use without any personal activities allowed, is indeed the COBO (Corporate Owned, Business Only) approach. This policy ensures that devices are purchased and owned entirely by the organization and are intended solely for professional use. Consequently, employees do not have the option to use these devices for any personal matters, which helps enhance data security and compliance by minimizing the risk of personal applications or behaviors that could lead to security vulnerabilities.

In contrast, COPE allows for personal usage, and while BYOD permits employees to use their personal devices for work-related tasks, it introduces complexity in terms of security and data management. CYOD provides a middle ground by letting employees choose from a selection of corporate-approved devices, but also permits personal use, which is not allowed in a COBO policy. Thus, COBO maintains strict control over device usage, aligning accurately with the scenario described in the question.