Final answer:
Microfibrillar collagen is a hemostatic agent that must be applied with a dry instrument to prevent adherence to the instrument and ensure effective clotting at the bleeding site.
Step-by-step explanation:
The hemostatic agent that must be applied with a dry instrument is microfibrillar collagen. This agent is designed to facilitate clotting and stop bleeding by attracting platelets and providing a surface for fibrin formation.
When using microfibrillar collagen, it has crucial that the instrument used to apply it is dry. This is because the moisture could cause the collagen to adhere to the instrument instead of the targeted bleeding site which could reduce the effectiveness of the agent and complicate the hemostasis process.