Which method is crucial for controlling bleeding effectively?

Direct pressure with a gauze pad is the most effective method for controlling bleeding. When applied directly to a wound, it helps to compress blood vessels and promotes clot formation, which is essential for stopping the flow of blood. This technique not only minimizes blood loss but also allows for the body's natural healing processes to begin.

While elevating and immobilizing a limb can assist in reducing blood flow to an injured area, and applying ice may help with swelling, these methods are secondary to the application of direct pressure. They do not actively compress the wound or stimulate clotting as effectively as direct pressure does. Additionally, slackening tight clothing can help in making the person more comfortable, but it does not directly address the issue of bleeding. Therefore, while these alternatives have their roles in wound management, direct pressure remains the primary and most critical action to take when trying to control bleeding.