Some proteins on the surface of a mammalian cell contain carbohydrates. These proteins are synthesized by _______ and the sugars are added in the _______.

a) cytoplasmic ribosomes; smooth endoplasmic reticulum

b) the Golgi apparatus; rough endoplasmic reticulum

c) ribosomes on the rough endoplasmic reticulum; Golgi apparatus

d) mitochondrial ribosomes; smooth endoplasmic reticulum

e) cytoplasmic ribosomes; plasma membrane