I am also having same problem .....................................................................
Since they needed workforce and the natives were uncooperative, the portuguese used their vast number of colonies in Africa to "import" workers
The most surprising thing for me personally was the set up of the trenches, there is a very good system where the front line is the first to attack or be attacked while the others are there as backups. If someone were to get hurt within the first trench, there are easily accessible routes for the soldiers to take to retreat to safety, on the contrary, if the front lines were in need of any reinforcement whatsoever, there is a clear way to travel for the soldiers to get more ammunition or man power.
Answer:
C. Challenges of settling untamed lands.
Explanation: