A User Is Planning to Host a Highly Available System

Multiple Choice

A user is planning to host a Highly Available system on the AWS VPC. Which of the below mentioned statements is helpful in this scenario?

A) Create VPC subnets in two separate availability zones and launch instances in different subnets.
B) Create VPC with only one public subnet and launch instances in different AZs using that subnet.
C) Create two VPCs in two separate zones and setup failover with ELB such that if one VPC fails it will divert traffic to another VPC.
D) Create VPC with only one private subnet and launch instances in different AZs using that subnet.