**Core Concept**
Type-I hypersensitivity, also known as immediate hypersensitivity, is a type of allergic reaction that occurs within minutes of exposure to an allergen. This reaction is mediated by IgE antibodies, which trigger the release of histamine and other chemical mediators from mast cells, leading to symptoms such as itching, swelling, and anaphylaxis.

**Why the Correct Answer is Right**
IgE antibodies play a central role in type-I hypersensitivity reactions by binding to allergens and triggering the activation of mast cells. This activation leads to the release of histamine and other chemical mediators, such as leukotrienes and prostaglandins, which cause the characteristic symptoms of an allergic reaction. The binding of IgE to the high-affinity IgE receptor (FcεRI) on mast cells is the key step in initiating this cascade of events.

**Why Each Wrong Option is Incorrect**
**Option A:** IgM antibodies are primarily involved in type II and type III hypersensitivity reactions, and are not typically associated with type-I hypersensitivity.
**Option B:** IgG antibodies are involved in type II and type III hypersensitivity reactions, and are also involved in immune responses against infections, but are not the primary mediator of type-I hypersensitivity.
**Option C:** IgA antibodies are primarily involved in mucosal immunity and are not typically associated with type-I hypersensitivity reactions.

**Clinical Pearl / High-Yield Fact**
Remember that type-I hypersensitivity reactions can be life-threatening in severe cases, such as anaphylaxis, and require prompt medical attention. Common examples of type-I hypersensitivity reactions include peanut allergy, latex allergy, and asthma.

**Correct Answer: C. IgE antibodies are the primary mediator of type-I hypersensitivity reactions.**