**Core Concept**
The development of cells of the immune system in an individual is a complex process that involves the maturation of hematopoietic stem cells into various types of immune cells, including T cells, B cells, and others. This process is crucial for the establishment of immune homeostasis and the prevention of immune-related disorders.

**Why the Correct Answer is Right**
The development of immune cells is known as immunogenesis or hematopoiesis. During this process, hematopoietic stem cells in the bone marrow differentiate into lymphoid progenitor cells, which then give rise to T cells, B cells, natural killer cells, and other immune cells. The maturation of these cells is influenced by a variety of factors, including cytokines, growth factors, and cell-cell interactions.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the process of immune cell development.
**Option B:** This option is incorrect because it is not a recognized term in the field of immunology.
**Option C:** This option is incorrect because it is a process related to the development of embryos, not immune cells.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the development of immune cells is a continuous process that occurs throughout life, and disruptions in this process can lead to various immune-related disorders, such as immunodeficiency or autoimmune diseases.

**Correct Answer:** C.