Small blood cell fragment that collects at sites of injury to begin the clotting process. A leukocyte B lymphocyte C reticulocyte D platelet E fibrinogen

The correct answer is (D) platelet.<br /><br />Platelets, also known as thrombocytes, are small blood cell fragments that play a crucial role in the clotting process. When there is an injury to a blood vessel, platelets gather at the site of the injury and form a plug to help stop bleeding. They release chemicals that activate the clotting cascade, leading to the formation of a stable blood clot.<br /><br />Here is a brief explanation of the other options:<br />(A) Leukocyte: A type of white blood cell involved in the immune response.<br />(B) Lymphocyte: A subtype of white blood cell that is part of the immune system, including B cells and T cells.<br />(C) Reticulocyte: An immature red blood cell.<br />(E) Fibrinogen: A plasma protein that is converted into fibrin during the clotting process, but it is not a cell fragment.