An independent agency is outside the office of the president and the executive departments, they don't have to answer to anyone and aren't swayed because they aren't under someone else's jurisdiction. Since they aren't linked to the office of the president they aren't influenced by the president. Hope this helped you :)
It would be the "c. Taklamakan" that was one of the most dangerous spots along the silk roads, since this area was both physically treacherous and lined with thieves