Explanation:

- 2011: This option is incorrect. The Maha Kumbh Mela is held every 12 years, the previous Maha Kumbh in 2001, making the subsequent one 12 years later in 2013.

- 2014: This option is incorrect. 2014 falls in the Ardha Kumbh cycle, which occurs every 6 years, not the 12-year Maha Kumbh cycle.

- 2015: This option is incorrect. Like 2014, it does not align with the 12-year cycle typical for the Maha Kumbh Mela.

- 2013: Correct Answer. The Maha Kumbh Mela was indeed held in Prayag (Allahabad) in 2013. The event took place as scheduled in the 12-year cycle, following its previous occurrence in 2001.