Answer – A and C
The AWS Documentation mentions the following
Many AWS customers choose to implement VPN connections because they can be a quick, easy, and cost-effective way to set up remote connectivity to a VPC. To enable redundancy, each AWS Virtual Private Gateway (VGW) has two VPN endpoints with capabilities for static and dynamic routing. Although statically routed VPN connections from a single customer gateway are sufficient for establishing remote connectivity to a VPC, this is not a highly available configuration. The best practice for making VPN connections highly available is to use redundant customer gateways and dynamic routing for automatic failover between AWS and customer VPN endpoints.
For more information on high availability for network connections please see the below link:
https://aws.amazon.com/answers/networking/aws-multiple-data-center-ha-network-connectivity/