The liver is an important biological structure classified as an organ, composed of various tissues working together for specific functions. It plays a crucial role in processes such as detoxification and digestion. In the levels of organization, the liver fits best under the category of 'organ'. ;
The liver is classified as an organ, as it is composed of various tissues that work together to perform essential functions. It fits best within the level of organization in biology that includes organs, organ systems, and organisms. Therefore, the appropriate answer is option B.
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