Identify three structures which provide support and protection in a eukaryotic cell.

The endoplasmic reticulum provides structure to the whole cell, or support, you could say.
The cell membrane protects the whole inside of the cell, and is the structure.
The cytoplasm provides support by holding everything up and it provides protection by surrounding all of the elements.

(I think)

I hope this helped

Cell Wall, Plasma Membrane and Peroxisomes.

Explanation:

In the case of plant eukaryotic cells, a cell wall formed by cellulose is the main structure responsible for provinding resistance and protection to cells, especially against dehydration. All eukaryotic cells also have a semipermeable plasma membrane composed of a double layer of phospholipids, with the function of controlling the entry and exit of molecules, protecting the internal content of the cell. Peroxisomes are cellular organelles responsible for producing the catalase enzyme, which transforms toxic oxygenated water molecules that are toxic to cells into non-toxic water and oxygen molecules. In other words, it protects cells against intoxication by byproducts resulting from cellular metabolism.