How are oases formed? A. Human made by digging or drilling into the ground
B. Low spots on the surface of the sand
C. Spring water bubbling up to the surface
D. All of the above

Explanation:

An oasis can be formed by an underground aquifer or river that creates enough pressure for water to seep to the surface, forming the oasis. These aquifers and natural springs allow for life to exist in harsh climates like the desert and are often well known to local herders, farmers, and travelers in the region.

C.

Explanation:

You can eliminate A.

Just because you drill into the ground, it doesnt cause gas. Unless it's to make a factory and causes polution by releaing chemicals into the air, the yes.

Eliminate D.

Because A doesn't seem right, it most likely not be all of them.

For B. I'm not sure

I'm not sure what Low Spots are unless you're talking about those small little holes made in the sand, it was mostly made by crabs

If I'm wrong, let me know. But, I hope this helped you! :)

this is a good question! i'll do some research and come back when i have the answer!