Respuesta :
Answer with explanation:
If we have to visualize important events in the history of the U.S. space program, we have to keep following things in mind
Year Program
19... Satellite A
19.. On Moon ....
.... ............
...... .........
So, while scaling , we will keep year , that is time on any of the axis and program on another axis.
→→The Appropriate option will be
(a) Time line