A food handler is assigned to monitor self-service food bars because customers may:

Self-service food bars present a significant risk for contamination from customers. A designated food handler must monitor these areas to ensure food safety protocols are followed. This includes preventing customers from using dirty plates for refills, touching food with their bare hands, or otherwise introducing pathogens to the food. The employee's primary role is to protect the food from contamination, remove any contaminated items, and maintain the overall safety and sanitation of the self-service line.

A. need help in selecting food: This is a customer service task, not the primary food safety reason for monitoring the bar.

B. attempt to steal food from the line: This is a loss prevention or security concern, not a food safety issue.

C. place too much food on their plates: This relates to portion and cost control, which is a business management issue, not a food safety one.

National Restaurant Association. (2017). ServSafe Manager Book, 7th Edition. Section 8, "Service," page 8.10.

U.S. Food and Drug Administration. (2017). FDA Food Code. Section 3-306.13, "Consumer Self-Service Operations."