Which statement is true regarding dual-stack lite?

A.
The softwire is an IPv4 tunnel over an IPv6 network.

B.
The softwire initiator (SI) encapsulates IPv6 packets in IPv4.

C.
The softwire concentrator (SC) decapsulates softwire packets.

D.
SRX devices support the softwire concentrator and softwire initiator functionality.

Explanation:
http://www.juniper.net/techpubs/en_US/junos/topics/concept/ipv6-ds-lite-overview.html