Which of the following sentences uses a colon correctly?

A. I like to go camping: but my friend likes to go shopping.

B. For my camping trip I packed a stove: a lantern: an ax: matches: and an emergency kit.

C. We visited four states last year: Colorado, Arizona, California, and Nevada.

D. We visited: Colorado, Arizona, California, and Nevada.

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.

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.