电阻R1、R3的电压U=UV1-UV2=14V-2V=12V，电路电流I= U R1+R3 = 12V 4Ω+8Ω =1A，∵I= U R ，∴电阻R2的阻值R2= U2 I = UV2 I = 2V 1A =2Ω；故选A．
