A prokaryotic cell is a type of cell that lacks a nucleus. The nucleus is the organelle that contains the genetic material of the cell, including the DNA. Therefore, option 3 is correct, as a prokaryotic cell does not have a nucleus.

Let`s dissect the other options to understand why they are not correct:

Option 1: Ribosomes are present in both prokaryotic and eukaryotic cells. Ribosomes are responsible for protein synthesis, and they can be found in the cytoplasm of the cell.

Option 2: The cell membrane is a vital component of both prokaryotic and eukaryotic cells. It acts as a selective barrier and controls the movement of substances in and out of the cell.

Option 4: Prokaryotic cells do have DNA, but it is not enclosed within a nucleus. Instead, the DNA is found in a region called the nucleoid, which is not surrounded by a nuclear membrane.

Therefore, the correct answer is option 3, as a prokaryotic cell does not have a nucleus.