The correct answer is answer choice A, incorrectly placed. The adjective clause 'where I found a great deal on a laptop' is describing the online store, and so should be placed directly after it, and not at the end of the sentence. Instead, the adjective clause seems as though it's describing day, which doesn't make sense.
The online store where I found a great deal on a laptop went out of business the next day.
Hope this helps!
