Answer – A, C and D
The AWS documentation mentions the following on the type of VPN connections
1. AWS Managed VPN - You can create an IPsec VPN connection between your VPC and your remote network. On the AWS side of the VPN connection, a virtual private gateway provides two VPN endpoints (tunnels) for automatic failover. You configure your customer gateway on the remote side of the VPN connection.
2. AWS VPN Cloudhub - If you have more than one remote network (for example, multiple branch offices), you can create multiple AWS managed VPN connections via your virtual private gateway to enable communication between these networks
3. Third-party software VPN appliance - You can create a VPN connection to your remote network by using an Amazon EC2 instance in your VPC that`s running a third party software VPN appliance. AWS does not provide or maintain third-party software VPN appliances; however, you can choose from a range of products provided by partners and open source communities.
For more information on VPN connections please refer to the below URL:
http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/vpn-connections.html