In the class I MHC pathway of antigen presentation,peptides generated in the cytosol are translocated into the endoplasmic reticulum in which of the following ways?
A)By ATP-dependent transport via the transporter associated with antigen-processing (TAP)1/2 pump
B)By passive diffusion
C)By receptor-mediated endocytosis
D)Through membrane pores
E)Via the proteasome