Answer:
D. The decreased pH of the cytosol
Step-by-step explanation:
The lysosome contains many different types of enzymes that are responsible for breaking down different types of biomolecules. If the lysosome breaks, the enzymes may leak out into the cytosol, which can be damaging to the rest of the cell. To prevent this from happening, a number of different protective mechanisms are in place. One such mechanism is the decreased pH of the cytosol compared to the lysosome. The lysosomal enzymes are optimized to function in an acidic environment, so if they leak out into the cytosol, their activity will be greatly reduced due to the higher pH of the cytosol. Additionally, the glycosylation of plasma membrane proteins can help to protect the cell from lysosomal enzymes by providing a physical barrier that prevents the enzymes from entering the cell. The reducing environment of the cytosol may also help to prevent damage by neutralizing any free radicals that are generated by the lysosomal enzymes. Overall, the decreased pH of the cytosol is the most important protective mechanism against lysosomal enzyme leakage.