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

c) Ribosomes on the rough endoplasmic reticulum; Golgi apparatus

Explanation:

Endoplasmic reticulum, a member of endomembrane system. If it contains ribosomes on their surface, they are called Rough Endoplasmic Reticulum (RER). RER is the site for protein synthesis.

Newly formed protein undergoes modification, one such modification is the addition of carbohydrate side chains to form glycoprotein. The protein then moves to the Golgi for modification.    

i think the answer is b.