Answer:
D) these connections are not user friendly
Step-by-step explanation:
DC current is the unidirectional movement of electric charge. The current generated by electrochemical cell is an example of direct current. DC current can flow through vacuum and also through semiconductors, insulators and wires.
The transmission of DC current is costly and complex compared to the AC current. Its voltage also cannot be stepped up or down so one cannot get the desired voltage.