Step 1: Understanding the concept of Triveni Sangam.
Triveni Sangam is the confluence of three sacred rivers: the Ganga, Yamuna, and the mythical Saraswati. The city of Prayagraj, formerly known as Allahabad, is located at the sacred Triveni Sangam and is a significant pilgrimage site in India.
Step 2: Analyzing the options.
(A) Nashik: Nashik is a holy city, but it is not located at the Triveni Sangam.
(B) Ujjain: Ujjain is another significant religious city, but it is not at the Triveni Sangam.
(C) Prayagraj: Correct — Prayagraj is the city where the Triveni Sangam is located.
(D) Haridwar: Haridwar is a holy city where the Ganga river flows, but it is not the location of the Triveni Sangam.
Step 3: Conclusion.
The correct answer is (C) Prayagraj, as it is located at the sacred Triveni Sangam.