The correct answer is (a) South West Khasi Hills.
South West Khasi Hills is the district with the lowest population density in Meghalaya. It has a population density of 100 people per square kilometer, which is much lower than the state average of 340 people per square kilometer. The district is located in the south-western part of Meghalaya and is bordered by the states of Assam and Manipur. The district is home to the Khasi people, who are the majority ethnic group in Meghalaya. The district is also home to a number of different tribes, including the Garo, Jaintia, and Mikir peoples. The district is a popular tourist destination, due to its beautiful scenery and its unique culture.
The other options are incorrect because they have a higher population density than South West Khasi Hills.
(b) South Garo Hills has a population density of 150 people per square kilometer.
(c) West Khasi Hills has a population density of 200 people per square kilometer.
(d) East Khasi Hills has a population density of 300 people per square kilometer.