**Core Concept**
The question is testing the understanding of Infant Mortality Rate (IMR) and its relation to the percentage of vaccinated children. The correct answer requires knowledge of the relationship between vaccination coverage and IMR.

**Why the Correct Answer is Right**
According to the Expanded Programme on Immunization (EPI), vaccination coverage of 90% can reduce IMR to 30 per 1000 live births. This is because vaccines protect children from vaccine-preventable diseases such as measles, pertussis, and tetanus, which are major causes of infant mortality. The reduction in vaccine-preventable deaths contributes to a decrease in IMR.

**Why Each Wrong Option is Incorrect**
* **Option A:** There is no direct correlation between reducing IMR by 30 and vaccination coverage of 90%. Reducing IMR by 30 implies a percentage decrease, whereas vaccination coverage is a percentage of children immunized.
* **Option B:** Reducing IMR to 30 does not necessarily mean reducing the absolute number of infant deaths to 30. IMR is a rate per 1000 live births, so a reduction to 30 implies a rate of 30 deaths per 1000 live births, not an absolute number of deaths.
* **Option C:** Reducing IMR to 30 does not imply a reduction in the number of vaccine-preventable deaths. Vaccination coverage of 90% can reduce the number of vaccine-preventable deaths, but reducing IMR to 30 is a rate, not an absolute number.

**Clinical Pearl / High-Yield Fact**
The Expanded Programme on Immunization (EPI) has established a target of vaccinating 90% of children to reduce IMR to 30 per 1000 live births. This highlights the importance of vaccination in reducing infant mortality.

**Correct Answer: C. Reducing IMR to 30 per 1000 live births.**