The instructions for protein synthesis originate in the cell's DNA, which is in the nucleus. Therefore the answer to your question is B. Transcription occurs when RNA polymerase uses DNA to create a complementary RNA strand for the protein that is being coded. The mRNA then undergoes processing, in which introns are cut out, and is then sent to the ribosome where corresponding amino acids are brought from the cytoplasm of the cell and are arranged in the order necessary to create the protein.
So the answer to the question is B.
