Idon't understand prepositional phrases. they just don't make sense to me how do i know what is a prepositional phrase

How did magellan's discovery of what is now considered the philippines directly affect the native populations that were living there? a.they disappeared deep into the new land and started another settlement b. they became aggressive after having a new religious view upon them c. they became restless to travel the world on the ships they encountered d.they became angered over losing their lands' raw goods like fruits and spices