How did the hundred years' war affect the medieval structure of feudalism, in which vassals owed military service to the king?

a.
the vassal system became more important in winning battles and holding conquered territory for the king.

b.
the introduction of the longbow and cannon made the vassal system more efficient.

c.
the need for a larger, standing army with greater mobility made the vassal system obsolete.

d.
the vassals became commanders of mercenary armies paid by the king to fight.

the answer would more than likely a.)falling crop prices  

hope the answer is right and ,either way have a nice day.

the viking voyages took place during the middle ages, which was about this time. 500 to 1350. the viking voyages took place during the middle ages, which was about this time.

the viking voyages took place during the middle ages, which was about this time. 500 to 1350. the viking voyages took place during the middle ages, which was about this time.

where is the map if i see it i can give you the answer