What is the main feature of a eukaryotic cell?

The defining characteristic of a eukaryotic cell is the presence of a membrane-bound nucleus. This structure houses the cell's genetic material (DNA), separating it from the cytoplasm and allowing for more complex regulation of gene expression and DNA replication. Eukaryotic cells can be found in a wide range of organisms, including animals, plants, fungi, and protists, highlighting their diversity and complexity.

Other characteristics of eukaryotic cells may include various organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus, which are involved in different cellular functions. The presence of a membrane-bound nucleus is a key feature that distinguishes eukaryotes from prokaryotes, which lack this structure and have their genetic material located in a nucleoid region without a surrounding membrane.

In contrast, prokaryotic cells, such as bacteria and archaea, do not possess a nucleus, making option A incorrect. While some eukaryotic organisms are unicellular, such as yeast and certain protists, eukaryotic cells can also be part of multicellular organisms, ruling out option C. Chloroplasts are specific to plant cells and some protists, thus not applicable to all eukaryotic cells,