Final answer:
The social worker should recommend placing the youth in a secure residential facility if the safety and welfare of the community are at risk.
Step-by-step explanation:
In this scenario, the social worker should recommend that the youth be placed in a secure residential facility if the safety and welfare of the community are at risk (option C). This is because the youth has a history of armed robbery and repeated drug-related offenses, which pose a potential threat to the community. Placing the youth in a secure residential facility would ensure that the community is protected while also providing an opportunity for rehabilitation and intervention.