A B <---> C D If the concentration of D is decreased, the equilibrium will: shift right and the concentration of "B" will decrease shift left and the concentration of "B" will decrease shift left and the concentration of "B" will increase shift riA B <---> C D If the concentration of D is decreased, the equilibrium will: shift right and the concentration of "B" will decrease shift left and the concentration of "B" will decrease shift left and the concentration of "B" will increase shift right and the concentration of "B" will increaseght and the concentration of "B" will increase