Question

Which of the following geographic features most likely hindered the Byzantines from expanding north of Italy?

a major river

a sea

mountainous terrain

desert terrain

Answer 1

I'd pick mountainous terrain.

For why I would do that, the Byzantines didn't have too many troubles in crossing major rivers - their empire encompassed a huge array of lands with a number of these waterways. And we're talking about northern Italy, so there wouldn't be an inland sea there. There are also no deserts within continental Europe. The climate just isn't right for those. So that leaves only one major geographical feature that would have been a problem for the Byzantines - mountainous terrain.

However, it can also be said that hostile peoples were also another factor which prevented their movement north - or in permanently keeping Italy as an extension of the empire.