Final answer:
The von Willebrand factor (vWF) floats aground in the blood with platelets.
Step-by-step explanation:
The correct answer is a) Platelets. von Willebrand factor (vWF) floats aground in the blood with platelets. vWF is an adhesive protein that binds to platelets and helps in their adherence to damaged blood vessels. It plays a crucial role in blood clotting by mediating the initial adhesion of platelets to the site of injury.