An experiment was done to test how four different treatments affected the permeability of the cell surface membranes and tonoplasts in beetroot cells. The vacuoles of beetroot cells contain a red pigment. This pigment is unable to diffuse through the tonoplasts or the cell surface membranes. $1\,\text{cm}^3$ cubes were removed from beetroot tissue and rinsed in running water for 20 minutes to wash away any pigment that had leaked from cells that were damaged. Two cubes were then put into each of four test-tubes, each containing a different substance, and left to stand for five minutes. Which row gives a correct explanation for the observation recorded for one of the treatments?
- Adilute hydrochloric acid; contents of test-tube stay clear; membrane proteins have been denatured
- Bethanol; contents of test-tube turn red; lipids, including membrane phospholipids, have dissolved
- Cwater at $20\,^{\circ}\text{C}$; contents of test-tube stay clear; membrane proteins have been denatured
- Dwater at $80\,^{\circ}\text{C}$; contents of test-tube turn red; lipids, including membrane phospholipids, have dissolved