Multiple choice this major site of protein synthesis has ribosomes attached to it and protects proteins within its folds from being exposed to the cell’s internal environment.

a. rough endoplasmic reticulum
b. smooth endoplasmic reticulum
c. golgi apparatus

Its a

Rough endoplasmic rectulum

Or RER.

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.