Which two commands should you use?

10.1.1. Which two commands should you use?

A.
ip helper address 10.10.1.1 under interface FastEthernet0/0.100

B.
option 150 ip 10.10.1.1 under dhcp pool Phones

C.
default-router 10.100.1.1 under dhcp pool Phones

D.
subnet prefix-length 24 under dhcp pool Phones