What is the minimum number of subnets that need to be configured in the VPC?

A company wants to implement their website in a virtual private cloud (VPC). The web tier will use an Auto Scaling group across multiple Availability Zones (AZs). The database will use Multi-AZ RDSMySQL and should not be publicly accessible.

What is the minimum number of subnets that need to be configured in the VPC?
A . 1
B . 2
C . 3
D . 4

Answer: B