Final answer:
The mistake made by the buser is cleaning the garbage can near food.
Step-by-step explanation:
The mistake made by the buser is option c. He cleaned the garbage can near food.
Scrubbing a garbage can in the dry-food storage area can lead to cross-contamination. The food stored in the area can be contaminated with the detergent or any potential residue left behind from the cleaning process. It is important to clean and sanitize garbage cans away from food storage areas to maintain food safety.