Answer:
Hi! An interjection as a part of speech is basically an exclamation ("ah!," "dear me!"). This question is asking us to find the sentence that correctly uses an interjection.
The first choice, "I mixed the wrong paints together, Oops!" is INCORRECT because it uses a comma (,) instead of a period (.).
The second choice, "I mixed the wrong paints together oops!" is INCORRECT because the sentence runs on. In this case, some sort of interruption would be required before the interjection.
The fourth choice, "I mixed the wrong paints together. oops!" is INCORRECT because the first "o" in "oops" is not capitalized.
Therefore, the third choice, "I mixed the wrong paints together, oops!" is CORRECT.
I hope this helps you! Have a great day.