Question

which is a complete sentence? layers and layers of cheese, lettuce, tomatoes, and onions. wouldnt be able to produce red blood cells without a skeleton. sugar and salt dissolve easily in water.

Explanation:

A complete sentence has a subject and a predicate. "Layers and layers of cheese, lettuce, tomatoes, and onions" is a noun - phrase without a verb. "Wouldn't be able to produce red blood cells without a skeleton" lacks a clear subject. "Sugar and salt dissolve easily in water" has a subject "sugar and salt" and a predicate "dissolve easily in water".

Answer:

Sugar and salt dissolve easily in water.