Platelets' Role in Blood Clotting

Steps:

• Recall blood components: plasma (liquid), platelets (cell fragments), red blood cells (oxygen carriers), white blood cells (immune defenders).
• Understand wound healing: injury triggers clotting to seal the wound and prevent blood loss.
• Identify clotting process: platelets aggregate at the site and release chemicals to activate fibrinogen into fibrin fibres.
• Confirm: fibrin fibres form a mesh that seals the wound, directly stimulated by platelets.

Why B is correct:

• Platelets release clotting factors that convert fibrinogen in plasma to fibrin, forming fibres to seal wounds, as per the hemostasis mechanism.

Why the others are wrong:

• A. Plasma provides clotting factors but does not actively stimulate fibre formation; it is the medium.
• C. Red blood cells transport oxygen and do not participate in fibre production or clotting.
• D. White blood cells combat infection but play no direct role in forming sealing fibres.

Final answer: B