The correct answer is
<span>c. The sea on three sides
Constantinople can only be attacked from one side. This causes armies to get caught in passages towards Constantinople and to not be able to sack the city since they don't have to think about the city being besieged fro mall sides. It is located on an excellent piece of land for defending and being like a turtle.</span>
Germany first overseas empire
The correct answer is the Gadsden Purchase.
The Gadsden Purchase, which was necessary for the trans-contintental railroad, adding the final bit of the US/Mexico border.