option D is correct
i also think option C i correct here bcoz of below line
the prestige of a kingdom depended upon the number of taxes that it was able to levy on its people.
but we should think that how the prestige should define i mean they want to tell what is the definition of prestige here by writing above line in the passage
so that if some one do its work in more intensity they are more prestige on their work so that here
the prestige of a head-hunter depended upon the number of heads he could gather
AND
the prestige of a kingdom depended upon the number of taxes he could levy