I didn’t realize option A was free when I made my comment.

I still think I’d go with option B though. You’ll be happier in the long run.

I would be concerned that if you keep it, they will try to charge you for it anyway. If you do go with option A, make absolutely sure it’s going to be free. Get it in writing. You definitely don’t want to pay for something you didn’t ask for that isn’t what you wanted.

There is also a possible option C, which is keep it for now and refuse to pay for it. Then you can change it later. Since they weren’t supposed to put in a backsplash at all, you should have received just drywall there. It’s cheaper and easier for them to leave it than to pull it out and drywall it so it matches what you had agreed on. You would have every right to ask them to put it in the agreed upon condition. This would add additional work and expense down the road if you wanted to change it though.