You plan to deploy five virtual machines to a virtual network subnet. Each virtual machine will have a public IP address and a private IP address. Each virtual machine requires the same inbound and outbound security rules.
What is the minimum number of network interfaces and network security groups that you require? To answer, select the appropriate options in the answer area. NOTE: Each correct selection is worth one point.
Answer: 
Explanation:
Box 1: 5
A public and a private IP address can be assigned to a single network interface.
Box 2: 1
You can associate zero, or one, network security group to each virtual network subnet and network interface in a virtual machine. The same network security group can be associated to as many subnets and network interfaces as you choose.
References: https://docs.microsoft.com/en-us/azure/virtual-network/security-overview