4.如圖(5)所示之電路,若v(t) = 20sin(5t) V,則電路總電流i(t)為何? (A) 2 sin(5t+45°) A (B) 2 sin(5t-45°) A (C) 2sin(5t-45°) A (D) 2sin(5t+45°) A