Hi Chloe.
The error here is “tastes great” as this can be only used when talking about a single unit, while we are currently talking about two units (peanut butter and jelly).
The correct way to phrase this is:
“Peanut butter and jelly are two products that taste great by themselves and taste great together, too.”
I hope this helps!
It is the letter D. Dear Sir.
You need to find the topic of the reading then highlight it blue then you find anything that supports the writing or claim and highlight it green and the find any main points that you think most help the writing and highlight it red