**Core Concept**
The HDCV (Human Diploid Cell Vaccine) schedule for rabies involves a series of injections to provide immunity against rabies virus. This schedule is crucial in preventing the development of rabies after exposure.

**Why the Correct Answer is Right**
The HDCV schedule typically consists of a series of intramuscular injections, with the first dose administered immediately after exposure and subsequent doses given on days 3, 7, 14, and 28. This schedule is based on the immune response generated by the HDCV, which takes time to develop. The HDCV stimulates the production of antibodies against the rabies virus, providing protection against the disease.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not specify the HDCV schedule accurately.
**Option B:** This option is incorrect as it does not align with the established HDCV schedule for rabies.
**Option C:** This option is incorrect as it does not provide the correct number of doses or the timing of the injections.

**Clinical Pearl / High-Yield Fact**
It is essential to administer the first dose of HDCV immediately after exposure to rabies, as this provides a rapid immune response and helps prevent the development of the disease.

**Correct Answer: D.**