蟲: can't fight now.

too late. the only thing you can do is to obey yoru boss' orders. You have to document everything in the meeting and follow up with each items. If it failed, you ahve the written docuemnts to show it was th team's decision, i.e. D and your boss's decision. Meeting minutes is very useful here. record who were in the meeting, what topics or questions discussed, especially what D and your boss said in teh meeting, what was decided and who would follow up on the action items.

Also, not sure how well you know your boss' boss. Taht is another way, escalate to teh next level. But it is risky. it depends on yoru relationship with the big boss. If he does not know you or your work, better not since he will reply on his report (your boss) opinions.