Final answer:
Selectins are the cell adhesion molecules responsible for mediating transient interactions between leukocytes and the endothelium at inflammation and clotting sites.
Step-by-step explanation:
The type of cell adhesion molecule that mediates transient interactions between circulating leukocytes and vessel walls at inflammation and clotting sites is Selectins. Selectins play a critical role during blood clotting, allowing platelets to adhere to the wall of damaged blood vessels and initiating a series of reactions that lead to clot formation. This group of glycoproteins is responsible for transient cellular adhesion, which is crucial in situations where a quick response is required, such as during inflammation or when a blood vessel is damaged and needs to be repaired.