Which of the following branch circuits is NOT suitable for kitchen countertop receptacles?

The reason a 30 AMP circuit is not suitable for kitchen countertop receptacles is because the National Electrical Code (NEC) specifically requires that countertop receptacles in dwelling units be supplied by either one 20 AMP circuit or two 15 AMP circuits. This is to ensure that adequate capacity and safety are maintained for the typical load conditions in a kitchen, where multiple appliances may be used simultaneously.

A 30 AMP circuit is typically reserved for larger appliances such as dryers or water heaters that have much higher power requirements. Using a 30 AMP circuit for kitchen countertop receptacles could potentially lead to issues, including the possibility of overloading smaller appliances that are not designed to handle that amperage, posing a risk of fire or electric shock. The focus in kitchen design is on functionality and safety, emphasizing circuits that are appropriately rated for the specific types of equipment that will be used there.