In central asia, oil and natural gas resources are most commonly found a. in the plains of kazakhstan b. in the steppes of mongolia c. near the caspian sea d. near the mountains of western china

Your "near the Caspian Sea".

These people would actually use this material for some kind of fishing which I'm not sure of how they would do this. But, I was reading some information further more to understand, and I learned that they would use this in some type of " Sturgeon fishing" which would then somehow would relate to why this would be around some sea, but overall, your correct answer would be (option C).