**Core Concept**
The appearance of immunoglobulins (antibodies) is a key aspect of the humoral immune response, which is the body's defense mechanism against infections. Immunoglobulins are produced by B cells (a type of lymphocyte) and play a crucial role in neutralizing pathogens and toxins.

**Why the Correct Answer is Right**
The first immunoglobulin to appear following infection is IgM. This is because IgM is produced by B cells very quickly after exposure to an antigen, typically within 3-5 days. IgM antibodies are large and have a pentameric structure, which allows them to effectively agglutinate pathogens and mark them for destruction. The production of IgM is a critical step in the early stages of an immune response, as it helps to neutralize pathogens and prevent their spread.

**Why Each Wrong Option is Incorrect**
**Option A:** IgG is the most abundant immunoglobulin in the blood and provides long-term immunity, but it is not the first to appear following infection.
**Option B:** IgA is primarily found in mucosal surfaces and provides protection against pathogens that enter the body through these routes, but it is not the first immunoglobulin to appear following infection.
**Option C:** IgE is involved in allergic reactions and the elimination of parasites, but it is not the first immunoglobulin to appear following infection.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that IgM antibodies are often used as a marker of recent infection, as they are produced in response to new antigens and can persist in the blood for several weeks.

**Correct Answer: C. IgE is involved in allergic reactions and the elimination of parasites, but it is not the first immunoglobulin to appear following infection.