Passage: Dhaka is Bangladesh's capital and largest city. There are 12 city corporations which hold mayoral elections: Dhaka South, Dhaka North, Chittagong, Comilla,  Khulna, Mymensingh, Sylhet, Rajshahi, Barisal, Rangpur, Gazipur and Narayanganj. Mayors are elected for five-year terms. Altogether there are 506 urban centres in Bangladesh among which 43 cities have a population of more than 100000.

Question: How many cities hold mayoral elections?
12