What organelle functions as the site of protein synthesis in the cell?

The proteins in a cell are produced by Ribosomes. They are modified however by the endoplasmic reticulum as well as well as the Golgi apparatus. For the purpose of this question the actual synthesis occurs at the Ribosomes as these are small multiple part cellular machines that interpret (Translate) RNA into the final proteins. This question implies a bound site however and the Ribosomes can be free moving in the cytoplasm of the cell. The rough ER is the site that these bind and stay stationary for a time. The best overall answer to satiate a pedantic instructor would be to say.

"The ribosomes attached to the rough ER function as the major site for protein synthesis."