Final answer:
The best statement that illustrates how people in Indiana changed their environment in the 1800s is that they dug canals to connect waterways, significantly altering the landscape to improve transportation and stimulate economic growth.
Step-by-step explanation:
The statement that best shows how people changed their physical environment in Indiana in the 1800s is: b. they dug canals to connect different waterways. In the 1800s, the construction of canals was a transformative development in the physical landscape, as Americans sought to improve transportation, connect different regions, and promote economic growth. The Erie Canal is an example of this effort, which, completed in 1825, fundamentally changed commerce by linking the Great Lakes with the Eastern seaboard and allowing goods to flow more freely between these regions. Indiana, along with other states, played a pivotal role in this era of internal improvements, which saw the creation of a vast network of canals that facilitated the transportation revolution.
The extensive system of transportation networks, including roads, canals, and railroads, altered the physical environment by carving pathways through the wilderness, thereby facilitating the expansion of industries, migration to the Western states, and national integration. This era's transformative energy reflected America's ambitious spirit and the vision that a connected country would lead to progress, prosperity, and the furtherance of the republic's ideals.