Where should the dash (es) go in this sentence?

I only had one thing on my mind this Halloween candy corn.

A. I only had one thing on my mind this Halloween-candy corn.

B. I only had one thing on my mind this-Halloween-candy corn.

C. I only had one thing on-my mind this Halloween candy corn.

A. I only had one thing on my mind this Halloween-candy corn.

Explanation:

In English, a dash is a horizontal line in the middle of a line of text and it's used to indicate added emphasis, an interruption or a pause. In other words, dashes subtly change the tone of the sentence to make a more emphatic idea.

In this example, the person is talking about what it's on their mind: candy corn.

If you take a look at the options given, you can see that the one that puts emphasis on the candy corn (which is the one thing on the mind of the person) would be option A. Remember also that dashes indicate a pause, when you read options B and C pausing at where the dash is, the sentence doesn't sound right and in the case of option C it even sounds odd as if it didn't make any sense.

Thus, the correct answer is A.