**Core Concept**
DPT vaccine is a combination vaccine that protects against diphtheria, pertussis (whooping cough), and tetanus. It contains inactivated or killed antigens from these three pathogens, which stimulate an immune response to prevent infection.

**Why the Correct Answer is Right**
The DPT vaccine is given in a series of doses to children, typically starting at 6 weeks of age. The vaccine contains diphtheria toxoid, which inactivates the diphtheria toxin, and tetanus toxoid, which inactivates the tetanus toxin. The pertussis component of the vaccine can be either whole-cell or acellular, depending on the formulation. The acellular pertussis vaccine is less likely to cause side effects, such as fever and local reactions, but may not be as effective in preventing pertussis.

**Why Each Wrong Option is Incorrect**
**Option A:** The DPT vaccine does not contain live or attenuated pathogens, making it safe for use in individuals with weakened immune systems.
**Option B:** The DPT vaccine is not a single-dose vaccine; it requires multiple doses to provide long-term protection.
**Option C:** The DPT vaccine does not protect against Hib (Haemophilus influenzae type b) disease.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the DPT vaccine is not a substitute for pertussis booster shots, which are recommended for adolescents and adults to maintain immunity against pertussis.

**Correct Answer:** C. The DPT vaccine does not protect against Hib (Haemophilus influenzae type b) disease.