Client-side scripts run in the user's browser and are intended to improve or control the form experience. They can hide or show fields, make fields mandatory or read-only, set field values, modify choice list options, and display field or form messages. They should not be used as a true security control because users may bypass client behavior, and they do not directly secure database or backend access. Playbook access and user access are controlled through platform security, roles, ACLs, and application configuration, not ordinary client scripts. In CAD terms, client scripts are primarily for form behavior and user experience. Therefore, B is correct.