**Core Concept**
Infant Mortality Rate (IMR) is a crucial indicator of the overall health and well-being of a population. It reflects the number of deaths per 1,000 live births in the first year of life, making it a significant measure of a country's or region's healthcare infrastructure and access to maternal and child healthcare services.

**Why the Correct Answer is Right**
Orissa (also known as Odisha) has historically reported one of the highest IMR values in India, largely due to inadequate access to healthcare services, particularly in rural areas. The state's healthcare infrastructure, including the availability of skilled birth attendants, healthcare facilities, and emergency services, has been a significant concern. Furthermore, the state's poverty and socio-economic factors contribute to the high IMR. The National Family Health Survey (NFHS) data and other studies have consistently shown that Orissa has one of the highest IMR values in the country.

**Why Each Wrong Option is Incorrect**
**Option A:** Tamilnadu has made significant strides in improving its healthcare infrastructure and has one of the lowest IMR values in the country, making it an unlikely candidate for the highest IMR.
**Option C:** Maharashtra, despite its large population and urban-rural disparities, has a relatively better healthcare infrastructure and lower IMR compared to Orissa.
**Option D:** Kerala has consistently reported one of the lowest IMR values in the country, attributed to its well-developed healthcare system, high literacy rate, and strong government initiatives.

**Clinical Pearl / High-Yield Fact**
IMR is a sensitive indicator of a population's overall health status and can be influenced by factors such as access to healthcare services, maternal education, and socio-economic status. Understanding the regional variations in IMR can help policymakers and healthcare providers identify areas of improvement and allocate resources effectively.

✓ Correct Answer: B. Orissa