The correct answer is Gurugram.
Gurugram is a district in the Indian state of Haryana. It is located in the National Capital Region (NCR) and is one of the most populous districts in India. The district has a population of over 3 million people, with a population density of over 2,000 people per square kilometer.
Gurugram is a major industrial and commercial center. It is home to many multinational companies, including Google, Microsoft, and Samsung. The district is also a major tourist destination, with many historical and cultural sites.
Faridabad is the second most populous district in Haryana. It has a population of over 2 million people. The district is located in the southern part of the state and is a major industrial center.
Panchakula is the third most populous district in Haryana. It has a population of over 1 million people. The district is located in the northern part of the state and is a major tourist destination.
Ambala is the fourth most populous district in Haryana. It has a population of over 1 million people. The district is located in the eastern part of the state and is a major agricultural center.
In conclusion, Gurugram is the district in Haryana with the highest population density. The district has a population of over 3 million people and a population density of over 2,000 people per square kilometer. Gurugram is a major industrial and commercial center and is home to many multinational companies. The district is also a major tourist destination.