Which of the following is a type of cell that lacks a membrane-bounded nucleus?

Prokaryotic cells are characterized by the absence of a membrane-bound nucleus, which distinguishes them from eukaryotic cells. In prokaryotic cells, the genetic material is not enclosed within a nuclear membrane; instead, it is typically found in a region called the nucleoid. This fundamental difference is significant in understanding cellular organization and function.

Eukaryotic cells, on the other hand, do have a true nucleus that is enclosed by a nuclear membrane, along with various membrane-bound organelles. The term "multicellular" refers to organisms that consist of more than one cell, which can be either prokaryotic or eukaryotic, but does not specifically address the presence of a nucleus. Plant cells are a type of eukaryotic cell; they possess a nucleus and other organelles surrounded by membranes. Thus, the defining characteristic of prokaryotic cells, lacking a membrane-bound nucleus, solidifies its status as the correct answer.