Final answer:
Visitors such as unknown individuals should immediately be announced and escorted in a professional environment. This is a standard security measure in workplaces. For the reference information provided, caregivers are often the perpetrators of abuse against the elderly.
Step-by-step explanation:
In a professional environment, visitors that should immediately be announced and escorted in typically include unknown individuals. It is important from a security and protocol perspective that individuals who are not recognized by the company's security or staff are properly identified and accompanied. This ensures the safety and confidentiality of the workplace, as well as providing a welcoming and professional atmosphere for guests. The correct answer to the student's question is: c. Unknown individuals.
Regarding the reference information provided:
If elderly people suffer abuse, it is most often perpetrated by caregivers. This serious concern highlights the need for vigilant oversight and the establishment of trust and effective communication in the care of vulnerable populations.