Which two statements about IPv4 and IPv6 networks are true? (Choose two.)

A.
In IPv6, hosts perform fragmentation.

B.
IPv6 uses a UDP checksum to verify packet integrity.

C.
In IPv6, routers perform fragmentation.

D.
In IPv4, fragmentation is performed by the source of the packet.

E.
IPv4 uses an optional checksum at the transport layer.

F.
IPv6 uses a required checksum at the network layer.