I'm not really sure, but I think that the correct answer would be the third option.
I hope this helps !
Please let me know if it is correct or not.
As you know, water evaporates in heat, and tropical places are usually very hot! Tropical implies "ocean" so, when an ocean evaporates it leaves a sandy ocean floor, which is a desert, but there are lake sized "puddles" of salt water left over, which is why there is a big salt water lake in the middle of Utah.
The best answer is conversational
