Which of the following is essential for wound care in a casualty?

Applying pressure to control bleeding is essential for wound care in a casualty because it helps to stabilize the patient by minimizing blood loss, which is crucial in a traumatic situation. When an individual has sustained a wound that is bleeding, immediate and effective pressure application can help initiate hemostasis, allowing the body to start the natural healing process. In many emergencies, uncontrolled bleeding can lead to shock and, if not addressed swiftly, may result in death.

The other options do not promote effective wound care. Bathing the wound in saline solution, while it may help in some situations, is not as critical as directly addressing bleeding, especially in a tactical environment where time is of the essence. Keeping a wound exposed to air can increase the risk of infection and may not be suitable unless specifically indicated. Using unclean materials to dress the wound could introduce further contaminants, leading to infection and complications that could worsen the casualty's condition. Therefore, controlling bleeding through direct pressure is the most essential component in managing a wound effectively.