Who among the following can take protective custody of a child?

The answer is correct because protective custody of a child typically involves those who are specifically authorized and trained to intervene in cases of suspected abuse or neglect. Child protection investigators (CPI) have the expertise to assess situations where a child's safety is at risk and can make decisions based on their training to ensure the child's immediate well-being. Law enforcement officers are also empowered to take protective custody in emergency situations, particularly when a child is in immediate danger. Doctors may become involved when there is a medical concern or injury that necessitates protective action to safeguard the child's health.

In contrast, other groups like parents, guardians, and family members do not have the authority to take protective custody unless they are acting in accordance with legal rights or protective orders. Similarly, personnel such as teachers, lawyers, and child psychologists may have roles in supporting children and reporting concerns but lack the authority to remove a child from a harmful situation. Therefore, option C is the most accurate reflection of those who can take protective custody of a child in Illinois.