Final answer:
True, substantial evidence indicates that ancient Mars had liquid water flowing on its surface, shaping the planet's geography with channels and gullies.
Step-by-step explanation:
The statement that running water played a major role in shaping Mars in ancient times is true. Geological evidence on Mars points to the existence of ancient rivers and lakes.
This can be seen from features such as channels and gullies observed on the Martian surface, suggesting that liquid water was once abundant on the planet. Additionally, data from rovers and orbitals have provided proof that Mars had a wet past. To understand the changes on Mars, we look at the planet's climate history, where billions of years ago, Martian temperatures would have been warmer, and its atmosphere more substantial to allow for the presence of liquid water.