Final answer:
Mop water should be changed at least once a week or as soon as it becomes visibly dirty or after cleaning a contaminated area. The correct answer is option B.
Step-by-step explanation:
Mop water should be changed out to prevent odor and contamination much more frequently than once a day or once a week. The correct answer is B. At least once a week, but ideally, mop water should be changed as soon as it becomes visibly dirty or if it has been used to clean a particularly dirty or contaminated area.
This helps maintain a sanitary environment and effectively cleans the surfaces. Using dirty mop water can spread dirt and bacteria around, leading to an unpleasant odor and potential health hazards. It is also good practice to thoroughly rinse the mop after use and allow it to dry to prevent the growth of mold and bacteria.