Answer:
2. cell wall
Step-by-step explanation:
The Cell wall is a thick layer made up of peptidoglycan that structurally supports and protects the cell. The cell wall is located just outside the semi permeable membrane. It give rigidity to the cell.
The cell wall also serves as a sieve or filter that allows or prevents the movement of molecule in or out of the semi permeable membrane.
An hypotonic solution is a solution that has a higher quantity of water when compared the quantity of solute dissolved in the water and this causes the solution to have a lower osmotic potential.
When a bacteria is growing in an hypotonic surrounding environment, there is a large amount of water present outside the cell. The cell wall of the bacteria serves as barrier and prevents the flow of water into the cell and this would prevent the cell wall of the bacteria from bursting open due to the rigidity of the cell wall.
Any bacteria that lacks a cell wall and is place in an hypotonic surrounding environment would swell and eventually burst open due the movement of water from hypotonic surrounding environment into the bacteria.