Question

what is the main function of the rough endoplasmic reticulum in a plant cell?
to break down sugar and release energy that the cell can use
to store water, waste, and nutrients, such as sugar, in the cell
to help ribosomes make proteins
to make lipids

Explanation:

The rough endoplasmic reticulum (RER) is studded with ribosomes. Its main role is to assist ribosomes in protein synthesis. Proteins made on the RER can be modified, folded, and then transported to other parts of the cell or secreted out of the cell. Breaking down sugar for energy is mainly done by mitochondria. Storing water, waste, and nutrients is a function of vacuoles. Making lipids is a role of the smooth endoplasmic reticulum.

Answer:

to help ribosomes make proteins