Answer:
Producing large quantities of proteins for secretion
Step-by-step explanation:
The endoplasmic reticulum is the tubular membrane-enclosed sac-like structure attached to the nucleus in the cell.
The endoplasmic reticulum attached to the nucleus appears rough in texture due to the presence of small organelles attached to the ER called ribosomes. The ribosomes function in the production of the protein molecule from the mRNA produced from the DNA.
The ribosome attached to the ER secrets proteins with peptide signal molecule which allows it to be secreted out of the cell thus is called secretory proteins like insulin.
Thus, the selected option is correct.