c. They are specialized.
These are called specialised cells.
A Eukaryotic cell contains a nucleus; more than one chromosome and is typically a multi-celled organism. Both plant and animal cells are eukaryotic cells.
For example, an epithelial cell can communicate and cluster with other epithelial cells thus, creating a epithelial tissue which now can serve to protect the body and serve as one component for excretion and homeostasis.