Final answer:
Eosinophils are not descended from the common lymphoid progenitor; instead, they originate from myeloid stem cells, unlike T cells, B cells, and NK cells which do originate from lymphoid stem cells.
Step-by-step explanation:
The cell type that is NOT descended from the common lymphoid progenitor is eosinophils. Lymphoid stem cells give rise to a class of leukocytes known as lymphocytes. This class includes T cells, B cells, and natural killer (NK) cells, all of which are integral to the body's immune system. Eosinophils, however, are derived from myeloid stem cells, not lymphoid stem cells. Myeloid stem cells give rise to a different set of formed elements that include erythrocytes (red blood cells), megakaryocytes for platelet production, and granular leukocytes such as neutrophils, eosinophils, and basophils. Therefore, option 4, eosinophils, is the correct answer to the question of which cell type is not derived from the common lymphoid progenitor.