Which of the following is the least complex structure in the body?

The least complex structure in the body is the ribosome. Ribosomes are molecular machines found within cells that are essential for protein synthesis. They are composed of ribosomal RNA and proteins, but they do not exhibit the organization and functions that characterize higher levels of biological organization like cells, tissues, and organs.

A cell represents a basic unit of life and is more complex than a ribosome, as it contains various organelles and structures that work together to sustain life. Tissues are groups of similar cells that perform a specific function, indicating an even higher level of complexity. Organs, made up of different types of tissues, perform complex functions necessary for the survival of the organism.

In summary, while ribosomes play a crucial role in cellular function, their structure and function are simpler compared to the intricate organization of cells, tissues, and organs.