The eighth Nagar Nigam (Municipal Corporation) declared in Uttarakhand State is :

Rishikesh
Kotdwar
Rudrapur
Srinagar

The correct answer is (c), Rudrapur.

Rudrapur is a city in the Kumaon region of Uttarakhand, India. It is the headquarters of Udham Singh Nagar district. The city is located on the banks of the Ramganga River, about 200 kilometers (120 mi) from the state capital, Dehradun. Rudrapur is a major industrial city and is known for its textile mills. The city is also a major tourist destination, with several temples and historical sites.

The other options are incorrect. Rishikesh is a city in the Garhwal region of Uttarakhand. It is a popular tourist destination, known for its temples and ashrams. Kotdwar is a town in the Garhwal region of Uttarakhand. It is a major commercial center and is known for its fruit orchards. Srinagar is a city in the Kashmir region of Jammu and Kashmir. It is the summer capital of India and is known for its lakes and gardens.