ADP released by platelets is involved in reducing blood flow through an injured vessel by

ADP released by platelets is involved in reducing blood flow through an injured vessel by
 a. causing the vascular musculature to remain contracted longer during the vascular spasm.
  b. causing the surface of nearby endothelial cells to become sticky so that platelets will stick to them, enhancing aggregation of platelets.
  c. causing the surface of nearby platelets to become sticky so that platelets will stick to them, enhancing aggregation of platelets.
  d. increasing the release of fibrinogen by activated platelets.
  e. all of these.