There are two numbers in Noun-Number: Singular and Plural. When we speak about one person / thing, we use the noun in singular form. When we speak about more than one person / thing, we use the noun in plural form.
In the sentence, we are referring to 'one' of three places. The subject is 'one' so we must use a singular noun. This rules out options A and B. Option D is incorrect because not all the places mentioned are cities. Hence, the right answer is option C.