**Core Concept**
Leucopoiesis is the process of producing white blood cells in the bone marrow. It involves the proliferation, differentiation, and maturation of hematopoietic stem cells into various types of leukocytes, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils.

**Why the Correct Answer is Right**
Leucopoiesis is a complex process involving multiple cell types and stages. It begins with the proliferation of hematopoietic stem cells, which then differentiate into myeloblasts, promyelocytes, and myelocytes. These cells eventually mature into specific types of white blood cells. **Option C**, "Formation of red blood cells," is not a part of leucopoiesis, as erythropoiesis is the process of producing red blood cells in the bone marrow.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so we cannot comment on it.
* **Option B:** This option is also not provided, so we cannot comment on it.
* **Option D:** This option is not provided, so we cannot comment on it.

**Clinical Pearl / High-Yield Fact**
During leucopoiesis, the bone marrow produces approximately 500 billion white blood cells per day, with the majority being neutrophils.

**Correct Answer: C. Formation of red blood cells.**