One Possible Disadvantage of Mediation-Arbitration as a Method for Third

One possible disadvantage of mediation-arbitration as a method for third party dispute resolution is:

A) The threat of arbitration makes successful mediation less likely to occur.
B) The mediator-arbitrator develops too much knowledge of the parties' concerns in the mediation phase and can no longer remain neutral in the arbitration phase.
C) The mediator-arbitrator can have too much power because of the threat of what they'll do in arbitration.
D) The parties may withhold information during the mediation because they fear the mediator-arbitrator will use the information against them in the arbitration phase.