Question

Which of the following sentences uses a colon correctly?

Answer 1

The correct answer is C. The first example cannot be correct because the colon simply doesn't fit there - a comma would fit better. The second one is also incorrect as you don't need to put a colon after every word, just once before the first word. The last example also doesn't need a colon, you can just enumerate these various states without the use of colon. So naturally, we are left with only one option, and that is C. 

Answer 2

C shows the correct use of the colon.   After the colon you may express a list.

You might question why D is not correct too.
It is not correct because the colon is not needed in that sentence.  You are stating the four states you visited, not expressing them as a list.