What Was the Major Obligation a Vassal Owed to His

What was the major obligation a vassal owed to his lord?

A) To sit in judgment on legal cases.
B) To perform military service, usually about 40 days a year.
C) A requirement to appear at his lord's court when summoned to give advice.
D) To train others for military combat in order to ensure the safety of the lord's land.
E) A responsibility to make financial payments to the lord on certain occasions.