## **Core Concept**
The Expanded Programme on Immunization (EPI) was launched by the World Health Organization (WHO) in 1974 to immunize children against six target diseases: **diphtheria**, **tetanus**, **pertussis**, **polio**, **tuberculosis**, and **measles**. The program aimed to immunize 80% of children in developing countries by 2000.

## **Why the Correct Answer is Right**
The correct answer, **DTP (Diphtheria, Tetanus, and Pertussis)**, was part of the EPI's original target diseases. The DTP vaccine is a combination vaccine that protects against these three serious bacterial infections. The EPI's focus on DTP, along with oral poliovirus vaccine (OPV), Bacillus Calmette-Guérin (BCG) vaccine against tuberculosis, and measles vaccine, was crucial in reducing the incidence of these diseases globally.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While BCG is indeed a vaccine, it is specifically for **tuberculosis**, which was already included in the EPI's original list. However, DTP is more comprehensive in targeting three diseases.
- **Option B:** This option might refer to **Hepatitis B** vaccine, which was introduced later into the EPI/WHO vaccination programs, not as part of the original EPI launch.
- **Option C:** This could potentially refer to another vaccine or combination, but it's not specified. Given the context, **DTP** is the accurate and direct part of the EPI.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the EPI's original goal was to immunize against **six major diseases**: diphtheria, tetanus, pertussis, poliomyelitis, tuberculosis, and measles. The **DTP vaccine** is critical in preventing **diphtheria**, **tetanus**, and **pertussis**, and its inclusion in the EPI has significantly reduced the mortality and morbidity associated with these diseases.

## **Correct Answer:** D. DTP.