Question

what is the main function of the nucleus in a plant cell?
to sort and package proteins and other substances
to send instructions to different parts of the cell
to produce steroid hormones
to store waste in the cell

Explanation:

The nucleus contains DNA which holds genetic information. It sends instructions via RNA to other cell - parts for processes like protein synthesis. Sorting and packaging of proteins is done by Golgi apparatus, steroid hormone production is not a main nuclear function, and waste storage is not a nuclear role.

Answer:

to send instructions to different parts of the cell