**Core Concept**
Rabies post-exposure prophylaxis (PEP) involves immediate wound cleaning, administration of rabies immune globulin, and a series of vaccinations using inactivated rabies virus vaccines. Human diploid cell culture vaccine (HDCV) is a type of inactivated vaccine used for PEP.

**Why the Correct Answer is Right**
The HDCV vaccine is administered on days 0, 3, 7, and 28 after exposure to rabies virus. This schedule enhances immune response and provides long-term protection against the virus. The vaccine works by stimulating the body's immune system to produce antibodies against the rabies virus, which helps to neutralize the virus and prevent infection.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not follow the standard HDCV vaccination schedule for post-exposure prophylaxis.
**Option B:** This option is incorrect because it does not accurately reflect the HDCV vaccination schedule for post-exposure prophylaxis.
**Option D:** This option is incorrect because it does not follow the standard HDCV vaccination schedule for post-exposure prophylaxis.

**Clinical Pearl / High-Yield Fact**
It is essential to complete the HDCV vaccination series as soon as possible after exposure to the rabies virus, as delaying vaccination can increase the risk of developing rabies.

**Correct Answer:** C. 7