Final answer:
option c,Direct pressure on the wound is the only initial way to stop serious bleeding. This triggers the body's response to form a blood clot and undergo coagulation to repair the injury.
Step-by-step explanation:
The only way to stop serious bleeding is by applying direct pressure on the wound, which would be option (c) in a multiple-choice setting. When a blood vessel is injured, the body begins a wound-healing response with the formation of a blood clot to stop the bleeding. Following this, vascular spasm would constrict the flow of blood, then a platelet plug forms, and coagulation occurs to repair the vessel wall and secure hemostasis. In situations where blood loss is significant and threatens life due to reduced perfusion, more complex interventions such as a tourniquet may become necessary; however, this is not the initial or 'only' method.
Other options mentioned, such as applying a tourniquet, elevating the wounded area, or pouring cold water on the wound, may not be effective or appropriate for all types of bleeding and could potentially worsen the situation.