Which is the default scheduler in YARN?

Which is the default scheduler in YARN?

A.
YARN doesn’t configure a default scheduler, you must first assign an appropriate scheduler
class in yarn-site.xml

B.
Capacity Scheduler

C.
Fair Scheduler

D.
FIFO Scheduler

Explanation:
http://hadoop.apache.org/docs/r2.4.1/hadoop-yarn/hadoop-yarnsite/CapacityScheduler.html