Which of these modern countries was NOT part of the Roman Empire?

The correct response is based on the historical context of the Roman Empire's territorial expansion and the regions it encompassed during its peak. Italy, as the heartland of the Roman Empire, was where Rome was founded and served as the center of its political, economic, and cultural life. Spain and France (then known as Gaul) were also integral parts of the Empire, with significant Roman settlements and administrative regions.

In contrast, when considering the territories that can be identified as modern-day Germany, it's essential to note that while parts of what is now Germany were influenced by Roman military activities and trade, the majority of the area was not fully incorporated into the Roman Empire. The Romans did engage with various tribes in Germania, and they established temporary military constructions and settlements along the Rhine and Danube rivers. However, the vast interior regions remained largely outside Roman control and were home to various Germanic tribes.

This distinction highlights why the modern nation of Germany did not have the same level of integration or administrative connection to the Roman Empire as the other listed countries, making it the answer to the question.