When AWS claims that VPC’s can operate in dual stack mode , what does that mean?

Answer options:

A.The VPC has operate on both the TCP and UDP protocol at the same time
B.The VPC can have an Internet gateway and Customer gateway attached at the same time
C.The VPC can operate in both IPv4 and IPv6
D.The VPC can have an Internet gateway and Virtual private gateway attached at the same time

Answer - C
The AWS documentation mentions the following
Your VPC can operate in dual-stack mode — your resources can communicate over IPv4, or IPv6, or both. IPv4 and IPv6 communication are independent of each other.
For more information on VPC and IPv6 please refer to the below URL:
http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/vpc-migrate-ipv6.html