**Core Concept**
The process of increasing the ability for phagocytosis of foreign bodies involves enhancing the immune system's capacity to engulf and digest microorganisms and other foreign particles. This is mediated by various immune cells, including neutrophils and macrophages, which recognize and bind to pathogens through specific receptors.

**Why the Correct Answer is Right**
The correct process of increasing phagocytosis is through the activation of the complement system, specifically the alternative pathway. This pathway is initiated by the presence of foreign particles, which leads to the formation of C3 convertase and the subsequent activation of C5, resulting in the production of C5a and C5b. C5a acts as a potent chemotactic agent, attracting phagocytic cells to the site of infection, while C5b forms the membrane attack complex, which helps to lyse the pathogen. Additionally, the alternative pathway is also involved in the opsonization of pathogens, making them more recognizable and susceptible to phagocytosis by immune cells.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely referring to the process of phagocytosis itself, rather than the mechanism of increasing its ability. Phagocytosis is the process by which immune cells engulf and digest foreign particles, but it is not the correct answer in this context.
* **Option B:** This option is not a valid choice, as it is incomplete and does not provide any information about the process of increasing phagocytosis.
* **Option D:** This option is also not a valid choice, as it does not provide any information about the process of increasing phagocytosis.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the alternative pathway of the complement system plays a crucial role in the innate immune response, particularly in the recognition and elimination of pathogens. Understanding this pathway is critical in developing effective therapeutic strategies to enhance phagocytosis and combat infections.

**Correct Answer:** C.