By "D" I'm assuming you mean "B."
Since B got the ball with clean hands, their options are: decline the penalty for A's foul and keep the ball, or accept the penalty, which results in a double foul, and we'll replay the down.
If B declines the penalty for A's foul, then enforce the IBB under ABO (and remember that once B gains possession, they become the offense. Enforce the 10 yards, set the chains, B 1/10 @ B42, clock on the snap.