Final answer:
Shellfish tags must be kept for 90 days beginning from the date of harvest, as this is crucial for maintaining traceability and ensuring food safety.
Step-by-step explanation:
The correct answer to the student's question is B) From the date of harvest. Shellfish tags are essential for tracking and ensuring the safety of shellfish products. The purpose of these tags is to maintain traceability from the point of harvest to the point of sale, which can be critical in the event of a foodborne illness outbreak. In this context, the 90-day retention period for shellfish tags is particularly important. Regulations typically require that these tags, which include critical information such as the date of harvest, be kept for a specified duration. It is from the date of harvest that the 90-day period begins. This timeframe allows for adequate traceability of the product through its shelf life.