A.They help the speaker feel less nervous.
B.They can make a speech seem more professional.
C.They help the speaker establish a formal tone.
D.They can make complex ideas easier to understand.
Visual aids and other media such as videos, pictures or presentations can help in delivering a speech or discussion because this gives additional detail that can easily be seen and analyzed by the readers. Therefore, the answer for this would be option D. It makes the complicated ideas easier to comprehend.