You Work Part-Time at a Local Diner and an Older

You work part-time at a local diner and an older employee tells you that one of the worst oversights he sees is the workers' disregard for the "danger" zone. Which of the following applies to this employee's warning?

A) keeping the freezer at 1°C
B) serving raw seafood without proper cooking techniques
C) keeping beef patties on a warm grill (57°C) for up to 3 hours
D) not disposing of egg shells immediately after use and allowing them to sit on countertops