Cacti typically grow in very dry climates with infrequent rainfall when it does rain the rain usally only penetrates a few inches into the soil which adaptation is most likey to a cactus survive in the dry climate

Its waxy outside keeps the water in and everything else out.

[content deleted] - user123802726recklesschicken

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link: