Pretty sure it is C because it it divisible by 3. If you divide 15 you get 5 and if you divide 6 you get 2.
<span>The obligations of serfs were to work for lords and knights. Serfs lives were much more difficult than that of a lord or knight. Serfs didn't have freedoms like the lords and knights. Knights would sometimes serve the lord as well but could also be the lord of a castle. Serfs didn't have that option.</span>
They were unprepared and exhausted for Washington's attack although they received warnings.