Question

which is a complete sentence? bears in yellowstone national park hibernate for about five months. nina fulfilling her dream of hiking to the top of mount st. helens. dairy products such as milk and cheese.

Explanation:

A complete sentence has a subject and a predicate. "Bears in Yellowstone National Park hibernate for about five months" has a subject (Bears in Yellowstone National Park) and a predicate (hibernate for about five months). "Nina fulfilling her dream..." is a fragment (no proper verb form like "is fulfilling"). "Dairy products such as..." is also a fragment (no predicate).

Answer:

Bears in Yellowstone National Park hibernate for about five months.