1. The Golgi apparatus has a cis face (convex/formed side) oriented towards the endoplasmic reticulum where materials arrive — statement I is true.
2. The trans face (concave/maturing face) is where processed materials are packaged and exit the Golgi — statement II is true.
3. The Golgi cisternae are involved in post-translational modification of proteins (glycosylation, proteolytic processing, etc.) — statement III is true.
4. Statement IV is incorrect because materials enter via the cis face and are released via the trans face (opposite of what IV states).
5. Thus I, II and III are the correct statements. Hence the correct answer is (3) I, II & III.