Explanation
Section: Understand Core Azure Services

Explanation
DevTest Labs creates labs consisting of pre-configured bases or Azure Resource Manager templates. By using DevTest Labs, you can test the latest versions of your applications by doing the following tasks:
Quickly provision Windows and Linux environments by using reusable templates and artifacts.
Easily integrate your deployment pipeline with DevTest Labs to provision on-demand environments.
Scale up your load testing by provisioning multiple test agents and create pre-provisioned environments for training and demos
https://docs.microsoft.com/en-us/azure/lab-services/devtest-lab-overview

Section: Understand Security, Privacy, Compliance and Trust
Explanation:
A network security group works like a firewall. You can attach a network security group to a virtual network and/or individual subnets within the virtual network. You can also attach a network security group to a network interface assigned to a virtual machine. You can use multiple network security groups within a virtual network to restrict traffic between resources such as virtual machines and subnets.
You can filter network traffic to and from Azure resources in an Azure virtual network with a network security group. A network security group contains security rules that allow or deny inbound network traffic to, or outbound network traffic from, several types of Azure resources.
In this question, we need to add a rule to the network security group to allow the connection to the virtual machine on port 80 (HTTP).
References:
https://docs.microsoft.com/en-us/azure/virtual-network/security-overview