The correct options are
C It takes place four times over the course of twelve years.
D The Kumbh Mela is celebrated across four sites in India.
The Kumbh Mela is the largest public gathering and collective act of faith, anywhere in the world. It takes place four times over the course of twelve years across four different pilgrimage sites. The location of the pilgrimage rotates between Haridwar on the Ganges in Uttarakhand, Ujjain on the Shipra in Madhya Pradesh, Nashik on the Godavari in Maharashtra, and Prayagraj at the confluence of the Ganges, the Yamuna, and the mythical Sarasvati in Uttar Pradesh.