Which statement correctly describes an accomplishment of kublai khan?
a.
after overthrowing the song dynasty, he moved the imperial capital from beijing to mongolia.
b.
under the yuan dynasty, he granted religious freedom to the chinese people.
c.
he improved the civil service system in china and ensured that jobs went to the most qualified people.
d.
he completed construction of the great wall of china to repel mongol invaders.