Question

identifying levels of organization
which is an organ?

Explanation:

An organ is a group of tissues that work together to perform a specific function. The first image is a single cell. The third image shows a tissue (a group of similar cells). The second image depicts the stomach, which is made up of multiple tissues (like muscle tissue, epithelial tissue etc.) working together to digest food.

Answer:

The second option (the stomach - like structure) is an organ.