Which of the following is the best definition of feudalism?

Which of the following is the best definition of feudalism?

a) a government in which kings are selected by their birthright to have exclusive control over a country
b) a government in which nobles have judicial, political, and military control over an area
c) a government in which leaders are elected to represent the ideas and opinions of the people
d) a government in which a leader takes office by force and leads with military authority