The adjuvant used in DPT vaccine is –

**Core Concept**
The adjuvant used in DPT vaccine enhances the body's immune response to diphtheria, pertussis, and tetanus antigens by stimulating the production of antibodies and activating immune cells.

**Why the Correct Answer is Right**
The adjuvant used in DPT vaccine is aluminum salts, specifically aluminum phosphate or aluminum hydroxide. These aluminum compounds work by activating the antigen-presenting cells (APCs), such as dendritic cells, which then present the antigens to T-cells, leading to a robust immune response. The aluminum salts also stimulate the production of cytokines, which further amplify the immune response.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a commonly used adjuvant in DPT vaccine.
**Option B:** This option is incorrect because it is not a suitable adjuvant for DPT vaccine.
**Option C:** This option is incorrect because it is not a widely used adjuvant in pediatric vaccines.

**Clinical Pearl / High-Yield Fact**
Aluminum adjuvants are commonly used in vaccines, but they can cause local reactions, such as redness, swelling, and pain, at the injection site. However, these reactions are usually mild and temporary.

**Correct Answer:** A. Aluminum salts (aluminum phosphate or aluminum hydroxide)