Terminal differentiation typically occurs in mature cells that have reached their final functional state. Among the options provided, hair cells and heart cells are examples of cell types that can undergo terminal differentiation.
However, if you are looking for a more definitive choice based on the context of terminal differentiation, epithelial cells often undergo terminal differentiation in various tissues.
If you need a single response based on common contexts, you might select epithelial cells, but it could also be valid to say hair cells or heart cells depending on the specific context of the question.
So, the correct answer would likely be: epithelial cells.