19 圖示放大器電路若電流源 I 為 1 mA、RB = 100 kΩ，RC = RL = 2 kΩ，Re = 100 Ω，電晶體電流放大率 β = 100，則電壓增益約為若干？ 
(A)-100
(B)-10
(C)-8
(D)-4