By definition, an organelle is a phospholipid-membrane bound compartment or structure in a cell with specific function/s. Ribosomes do not qualify to be called as organelles in this regard since they lack the aspect of being membrane-bound, hence considered particulate. However ribosomes can become membrane-bound when they associate with the endoplasmic reticulum.

Lysosome:
- Lysosomes are small spherical organelles found in animal cells.
- They contain digestive enzymes that help break down waste materials, cellular debris, and foreign substances.
- These enzymes function optimally in an acidic environment, which is maintained by the lysosomes.
- Lysosomes play a crucial role in the process of autophagy, where they digest and recycle damaged organelles and proteins within the cell.
- They also aid in the destruction of bacteria and other pathogens that enter the cell.

Centrosome:
- The centrosome is a small organelle found near the nucleus in animal cells.
- It consists of two centrioles, which are cylindrical structures made up of microtubules.
- The centrosome plays a crucial role in cell division, specifically in the formation of spindle fibers that help separate the chromosomes during mitosis.
- It also contributes to the organization and maintenance of the cell's cytoskeleton.

Ribosome:
- Ribosomes are small, spherical organelles found in both prokaryotic and eukaryotic cells.
- They are responsible for protein synthesis, where they translate the genetic information stored in the mRNA (messenger RNA) into a sequence of amino acids to form proteins.
- Ribosomes can either be free in the cytoplasm or attached to the endoplasmic reticulum (ER) in eukaryotic cells.
- They consist of two subunits, a large and a small subunit, that come together during protein synthesis.

Golgi Body:
- The Golgi body, also known as the Golgi apparatus or Golgi complex, is a membrane-bound organelle found in eukaryotic cells.
- It is involved in the modification, sorting, packaging, and transport of proteins and lipids within the cell.
- The Golgi body consists of flattened membranous sacs called cisternae, which are stacked on top of each other.
- Proteins and lipids enter the Golgi apparatus from the endoplasmic reticulum (ER) and undergo various modifications, such as adding sugar molecules (glycosylation), before being packaged into vesicles for transport to their final destinations.

Smallest Cell Organelle:
- Among the given options, the smallest cell organelle is the ribosome.
- Ribosomes are only a few nanometers in size and are present in large numbers within the cell.
- They can be found in the cytoplasm or attached to the endoplasmic reticulum.
- Their small size allows them to be involved in protein synthesis, which occurs in all cells.
- Ribosomes play a fundamental role in cellular processes and are essential for the production of proteins, the building blocks of life.