In most cells, insulin stimulates uptake of glucose by

In most cells, insulin stimulates uptake of glucose by
 a. penetrating the cellular membranes itself, and thereby providing a pathway for glucose to enter the cells.
  b. activating insulin receptors, which are themselves glucose transporters.
  c. stimulating the recruitment of glucose transporters to the membrane, which in turn facilitate the import of glucose.
  d. activating the transcription and translation of glucose transporter-genes, increasing their expression.
  e. altering the ratio of intracellular sodium concentrations to extracellular sodium concentrations in a way that favors co-transport of glucose and sodium.