Final answer:
Platelets are the formed element required for hemostasis.
Step-by-step explanation:
Hemostasis is the physiological process by which bleeding ceases. It involves three basic steps: vascular spasm, the formation of a platelet plug, and coagulation. Platelets, also known as thrombocytes, are required for hemostasis as they play a crucial role in the formation of a platelet plug. Therefore, the correct answer is 3) platelets.