Stem cells are responsible for a. red blood cell production. b. white blood cell production. c. platelet production. d. the production of all formed elements.

Stem cells are unique cells that have the ability to differentiate, or transform, into different types of cells in the body. They serve as the body's cell regeneration and repair system. In the bone marrow, there are a particular type of stem cells called hematopoietic stem cells (HSCs), which give rise to all of the blood cell types in the body, including red blood cells, white blood cells, and platelets. These blood cell types are also known as formed elements.

Now, let's look at each answer choice and determine if it is correct based on the information provided about stem cells and their role in the body: a. Red blood cell production: While stem cells do produce red blood cells, it is not their only function, so this choice is partially correct but incomplete. b. White blood cell production: Similarly, stem cells also produce white blood cells, but this is not their only function, so this choice is also partially correct but incomplete. c. Platelet production: Stem cells indeed produce platelets, however, this is not their only function, making this choice partially correct but incomplete. d. The production of all formed elements: This choice most accurately represents the role of hematopoietic stem cells, as they produce red blood cells, white blood cells, and platelets - all of the formed elements in blood.

Based on the provided information and analysis, the correct answer is: d. The production of all formed elements.