All of the above. Also, the amount of money can vary on wich type of housing, food, transportation, and entertainment you pay for.
C. Free writing ks the answer to your question.
<u><em /></u><em>it is very simple but very important
1 they do not make spelling mistakes...
2 they have a strong grammar concept...
3 they stay away from plagiarism
4 they try to summarize whole topic to make it easy to understand
5 they try to write different topics in comparison... :)</em>