How far is the last room in the cave from the Iowa border?

The distance from the last room in Niagara Cave to the Iowa border is accurately represented by three-quarters of a mile. This specific measurement is important for visitors and tour guides to understand the cave's proximity to notable geographical landmarks. Knowing this distance can enhance the tour experience by providing context about the cave's location and its significance in relation to the surrounding area, such as accessibility to the bordering state.

Choosing three-quarters of a mile as the correct answer helps reinforce information about the cave's geography and allows for a better understanding of the tour's layout and journey for guests. Thus, this choice is well-founded based on the cave's actual measured distance.