A colon is mostly used to show that you are going to make a list of things after the comma. So, having that in mind, the correct answer is the first option - I edited the article and found: comma splices, sentence fragments, and misplaced modifiers.
You listed three things here, therefore you have to put a colon. If you are going to mention only one thing, like in the other examples, a colon is not needed.
Answer:
the two middle pages of a magazine, often taken up by a single illustration or feature
Explanation:
Answer:
You will usually find a period at the end of a paragraph ,or even a sentence.
