Answer:
A) Allahabad
Step-by-step explanation:
It's a pilgrimage festival that takes place every 6 years in Allahabad & Haridwar, India.
Relegion: Hinduism
Reason: To bathe in the Holy waters of River Ganga & make them clean.
People who attend: About 30-50 million Hindus.
Disadvantages : It's a really crowded event & though River Ganga is considered pure & holy, many people bathing in it can make it dirty & unhygienic.
Hope it helps ⚜