"what must occur before a newly made polypeptide is secreted from a cell?
A. It must be translated by a ribosome that remains free within the cytosol
B. Its signal sequence must target it to the ER, after which it goes to the Golgi
C. Its signal must be cleaved off before the polypeptide can be enter the ER
D. Its signal sequence must target it to plasma membrane, where it causes exocytosis