Make this sentence concise and grammatically correct: When I looked at the results I couldn't figure out what was happening and then I looked in the appendix in my science textbook which showed me a similar result that I could use in my conclusion.

Since the results of my experiment were ambiguous, I consulted the textbook appendix and found an example with similar outcomes that enabled me to generate a conclusion.

What disorder causes loss of memory of events and knowledge that occurred or was learned before an injury or the onset of a disease? A. Stroke B. Anterograde Amnesia C. Retrograde Amnesia D. Traumatic Brain Injury (TBI)

C. Retrograde Amnesia

Choose the sentence that uses the comma correctly: Once, upon a time there was a princess. Once upon a time, there was a princess. Once upon a time there was, a princess.

Once upon a time, there was a princess.