Why might a writer choose to paraphrase a source?

When you see information in brackets, these are dialogue stage directions setting actor names

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

Which source would be the most credible choice for researching the life of anne frank?