A unit cannot cut a support that is used against her. Unit A will be dislodged.

Alright, thanks for that. I have one other question;

Say its the same situation as above, except that the army in A attacks the currently empty territory of D. At the same time, some other army moves into D and bounces army A back into territory A. Will he withdraw based on his position at A, or to a territory adjacent to D?

Your unit would be dislodged. I'm not sure what the exact definition of this rule is, but what comes to mind is the following explanation: "A unit can't cut a support that targets itself."

Basically, look at it this way. Those two units are a power of 2 in attempting to occupy your space. Your unit is a power of 1. Your unit will be dislodged in the absence of outside help or interference.

Hope this helped.

For your second question. It would resolve like this.

A bounce would occur at territory D. Both units will go back to their respective territories. Now, your unit will still be dislodged from that space because of the other two units. In this event, your unit will now have a retreat. However, you can not retreat to an area that resulted in a standoff, aka bounce. So you would retreat to any other adjacent space that wasn't where the incumbent unit came from.

Alright, thanks alot