A Solutions Architect has been given the following requirements for a company's VPC:
The solution is a two-tiered application with a web tier and a database tier.
All web traffic to the environment must be directed from the Internet to an Application Load Balancer.
The web servers and the databases should not obtain public IP addresses or be directly accessible from the public Internet.
Because of security requirements, databases may not share a route table or subnet with any other service.
The environment must be highly available within the same VPC for all services.What is the minimum number of subnets that the Solutions Architect will need based on these requirements and best practices?