- A cell membrane is a kind of cell structure
- The cell membrane provides support / protection for a cell
- So, the cell membrane is the cell structure that provides protection for a cell

- The cell membrane is the cell structure that provides protection for a cell
- An animal cell is a kind of cell
- Therefore, the cell membrane is the cell structure that provides protection for an animal cell

Hence, the cell membrane is the cell structure that provides protection for an animal cell
Which structure surrounds and protects an animal cell?
- A cell membrane is a kind of cell structure 
- The cell membrane provides support / protection for a cell 
- An animal cell is a kind of cell