**Core Concept**
IFN beta (Interferon beta) is a type of cytokine that plays a crucial role in the immune response, particularly in the context of viral infections and autoimmune diseases such as multiple sclerosis. It is part of the class II interferons, which are involved in antiviral, antiproliferative, and immunomodulatory effects.

**Why the Correct Answer is Right**
IFN beta is stimulated by viral infections, particularly those caused by RNA viruses. The stimulation of IFN beta is mediated by the recognition of viral double-stranded RNA (dsRNA) by the MDA5 (melanoma differentiation-associated protein 5) and Mx1 receptors. This recognition triggers the activation of the IFN beta promoter and the subsequent transcription of the IFN beta gene. The produced IFN beta then acts on nearby cells to induce an antiviral state, including the upregulation of antiviral proteins and the inhibition of viral replication.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while TNF alpha (tumor necrosis factor alpha) is a cytokine involved in inflammation and immune responses, it is not directly involved in the stimulation of IFN beta.

**Option B:** This option is incorrect because IL-1 beta (interleukin-1 beta) is a cytokine involved in the inflammatory response, but it is not directly involved in the stimulation of IFN beta.

**Option D:** This option is incorrect because while IFN gamma (interferon gamma) is a cytokine involved in the immune response, particularly in the context of cell-mediated immunity, it is not directly involved in the stimulation of IFN beta.

**Clinical Pearl / High-Yield Fact**
It is worth noting that IFN beta is used as a therapeutic agent in the treatment of multiple sclerosis, where it is administered to reduce the frequency of relapses and slow disease progression.

**Correct Answer:** C.