How did physical geography benefit and hinder both eastern and western roman empires?

Rich volcanic soil makes the Po and Tiber river valleys ideally suited for agriculture. Historian Mike Anderson notes that volcanic ash made the soil near Rome some of the best in all of Europe. ... The extra population later helped Rome's military expansion by providing a large supply of troops.

I THINK

A. - canada and the u.s 

C. england's numerous gold and silver mines made it a target for invasion