Which of the following is a common sign of pest infestation?

Evidence of droppings or shed skins is a common sign of pest infestation because these materials are direct indicators of pest activity. Many pests, such as rodents and insects, leave droppings that can vary in size and shape depending on the species. The presence of these droppings not only signifies that pests are in the area but can also help identify the type of pest involved. Shed skins are particularly associated with insects like cockroaches or moths that molt as they grow, providing another clear sign of an active infestation.

Other options, while potentially problematic in a food safety context, do not specifically indicate a pest problem. Signs of moisture might suggest a favorable environment for pests but do not confirm their presence. Visible pest control products might indicate that pest management efforts are in place but do not serve as direct evidence of an infestation. New products arriving with seals intact are a positive sign of safe food handling and storage procedures, showing that products have not been tampered with and reducing risk of pest contamination.