Presented this way I would have to go with B, but is this really a fair choice? The extra 3rd round pick, Golston, wasn't gotten because Dallas passed up on drafting Horn. They traded down and took Parsons because Horn was not available. If Denver had taken Fields instead of Surtain, who would Dallas have drafted, Parsons, or Surtain? I think we know the answer is Surtain, at 10.
Once Denver took Surtain, Dallas traded down because their targets were gone. At that point with Fields and Mac Jones on the board, I would have called Chicago and New England to see if I could work out a deal to move down. If the only deal they could make was with the Eagles then the choice was Slater or Parsons. or some other player like Phillips. I would have taken Slater. Not because Parsons isn't a good player but because I think offensive line is a bigger need than LB. The NFC East is full of top rated DTs. Having a stout offensive line is an imperative for Dallas. Lining up Connor Williams next to Tyler Biadasz scares me.
I think Parsons has the potential to help Dallas. The NFC East also has some fast RBs, like Barkley, Gibson and Sanders. Parsons has the ability to cut these guys off before they get too far upfield in the open. But I would rather control the ball with Zeke behind a powerful offensive line to help the defense. Just my opinion. That are a lot of ways to get through a draft successfully.