The correct answer is A. Deoghar.
Deoghar is a city and a municipal corporation in Deoghar district in the Indian state of Jharkhand. It is the headquarters of Deoghar district and is located on the banks of the Son River. Deoghar is a popular tourist destination and is known for its temples, including the Baidyanath Temple, which is one of the 12 Jyotirlingas. The city is also home to the Deoghar Airport.
Deoghar is known as the “city of waterfalls” because of the many waterfalls located in the area. The most famous waterfall in Deoghar is the Son Ghat Waterfall, which is located on the Son River. The Son Ghat Waterfall is a popular tourist destination and is known for its beauty.
The other options are incorrect because they are not known as the “city of waterfalls”. Ranchi is the capital of Jharkhand and is known for its universities and colleges. Koderma is a town in Jharkhand and is known for its coal mines. Gumla is a district in Jharkhand and is known for its tribal culture.