Which of the following is true about cells?
A.
Both eukaryotic cells and prokaryotic cells always contain both a true nucleus that is well-defined and organelles that are separated from the cytoplasm by membranes.

B.
In general, eukaryotic cells do not have a true nucleus or membrane-bound organelles, whereas prokaryotic cells contain both a nucleus and organelles enclosed by membranes.

C.
In general, prokaryotic cells do not have a true nucleus or membrane-bound organelles, whereas eukaryotic cells contain both a nucleus and organelles enclosed by membranes.

D.
Neither prokaryotic cells nor eukaryotic cells ever contain both a true nucleus that is well-defined and organelles that are separated from the cytoplasm by membranes.

Cell is the membrane-bound fundamental unit of life, in which all living things are composed. All living things can be divided into three basic domains: Bacteria, Archaea and Eukarya. The primarily single-celled organisms found in the Bacteria and Archaea domains are known as prokaryotes, which are made of prokaryotic cells while organisms in the Eukarya domain are made of the more complex eukaryotic cells. These organisms, called eukaryotes, including plants, animals, fungi etc.

Prokaryotic cells do not have a well-defined nucleus but the DNA molecule is located free-floating in the cell, termed as nucleiod (an open region containing DNA). Prokaryotic cells lack certain organnelles like mitochondria, Golgi apparatus, Endoplasmic reticulum etc. which are all found in eukaryotes, the organnelles are not membrane-bound, if present.

Eukaryotic cells have a well-defined nucleus surrounded by a nuclear envelope that consists of two lipid membranes, where the genetic material is stored and different membrane-bound organnelles to perform different functions within the cell.