Explanation: In Amplitude Modulation (AM), the modulating signal varies the amplitude of the carrier wave. When the carrier is modulated, sidebands are generated, carrying the information. The power contained in these sidebands adds to the carrier power. Therefore, during normal, undistorted modulation, the total average power of the transmitted signal increases compared to the unmodulated carrier. Since power is proportional to the square of current (P = I²R), an increase in average power results in an increase in the average antenna current. "Without carrier shift" is a critical condition. Carrier shift, also known as dynamic amplitude modulation or envelope distortion, indicates a change in the average amplitude or frequency of the carrier *during* modulation. This is a sign of non-linearity or improper operation in the modulator or final amplifier stage, leading to distorted audio. Therefore, an increase in antenna current *without* carrier shift is the clear indicator of proper, undistorted AM modulation. Options B, C, and D describe scenarios involving decreased current or the presence of carrier shift, both indicative of faulty or distorted modulation.