What can be used to determine a path from the head-end to a tail-end router when implementing SR-TE with a head-end, with little information on the network topology?

What can be used to determine a path from the head-end to a tail-end router when implementing SR-TE with a head-end, with little information on the network topology?
A . traffic controller
B . path computation engine
C . tail-end router
D . SNMP server

Answer: B