The correct answer is: The coastal regions.
The coastal regions are the most densely populated areas in India. This is due to a number of factors, including the availability of water, fertile land, and access to trade routes. The coastal regions are also home to a number of major cities, such as Mumbai, Chennai, and Kolkata.
The Imphal Valley is a relatively sparsely populated area. This is due to the fact that the valley is located in a mountainous region and is prone to natural disasters. The Imphal Valley is also home to a number of ethnic groups, which can make it difficult to develop infrastructure and services.
The hilly regions are also sparsely populated. This is due to the fact that the hills are difficult to access and are not suitable for agriculture. The hilly regions are also home to a number of tribal groups, which can make it difficult to develop infrastructure and services.
Remote border areas are the least densely populated areas in India. This is due to the fact that these areas are located far from major cities and are not well-connected to the rest of the country. Remote border areas are also home to a number of ethnic groups, which can make it difficult to develop infrastructure and services.