Which fact most clearly shows the difficulty in defending the Roman Empire against invasion?

Options:
As its heigh, the empire likely had a population as high as 100 million.

At its height, the empire comprised nearly 1.7 million square miles of land and water.

Over the course of its history, the Roman Empire built about 55,000 miles of paved roads.

The Mediterranean Sea stretches about 2,300 miles west to east and about 600 miles from Italy to the African coast

The fact that most clearly shows the difficulty in defending the Roman Empire against invasion is:

- At its height, the empire comprised nearly 1.7 million square miles of land and water.

This demonstrates the vast expanse of the empire, making it challenging to defend its borders and maintain control over such a large territory.

The fact that most clearly shows the difficulty in defending the Roman Empire against invasion is:

- At its height, the empire comprised nearly 1.7 million square miles of land and water.

Having such a vast territory to defend would have posed significant challenges for the Roman Empire in terms of resources, manpower, and logistics.

The fact that most clearly shows the difficulty in defending the Roman Empire against invasion is that, at its height, the empire comprised nearly 1.7 million square miles of land and water.

To understand why this fact indicates the challenge of defending the empire, we can look at the geographical size of the Roman Empire. With such an extensive territory, it was incredibly difficult to secure the entire empire's borders and prevent invasions from various directions.

The Roman Empire spanned across vast regions, including modern-day Italy, Greece, Turkey, Egypt, and parts of North Africa, among others. These territories were scattered across different continents, making it challenging to mobilize and deploy forces quickly to counter potential invaders. Additionally, the empire had to defend both land-based borders and its extensive coastline, which required a significant military presence.

With such a vast expanse to protect, the Roman Empire faced continuous threats from various neighboring peoples and tribes seeking to take advantage of any weaknesses in its defense. The size of the empire made it difficult to maintain a strong defensive front and respond swiftly to multiple incursions simultaneously. Hence, the sheer territorial expanse of the empire indicates the difficulty in defending it against invasion.