Explanation:

The Traffic Manager Contributor role is not related to Traffic Analytics. Traffic Manager is a service that provides DNS-based load balancing and traffic routing across different regions and endpoints. Traffic Manager Contributor is a role that allows you to create and manage Traffic Manager profiles, endpoints, and geographies1.
Traffic Analytics is a service that provides visibility into user and application activity in your cloud networks.
Traffic Analytics analyzes Azure Network Watcher network security group (NSG) flow logs to provide insights into traffic flow in your Azure cloud. With Traffic Analytics, you can visualize network activity, identify hot spots, secure your network, optimize your network deployment, and pinpoint network misconfigurations2.
To enable Traffic Analytics for an Azure subscription, you need to have a role that grants you the following permissions at the subscription level:
Microsoft.Network/applicationGateways/read
Microsoft.Network/connections/read
Microsoft.Network/loadBalancers/read
Microsoft.Network/localNetworkGateways/read
Microsoft.Network/networkInterfaces/read
Microsoft.Network/networkSecurityGroups/read
Microsoft.Network/publicIPAddresses/read
Microsoft.Network/routeTables/read
Microsoft.Network/virtualNetworkGateways/read
Microsoft.Network/virtualNetworks/read
Microsoft.OperationalInsights/workspaces/*
Some of the built-in roles that have these permissions are Owner, Contributor, or Network Contributor3.
However, these roles also grant other permissions that may not be necessary or desirable for enabling Traffic Analytics. Therefore, the best practice is to use the principle of least privilege and create a custom role that only has the required permissions for enabling Traffic Analytics4.
Therefore, to meet the goal of ensuring that an Azure AD user named Admin1 is assigned the required role to enable Traffic Analytics for an Azure subscription, you should create a custom role with the required permissions and assign it to Admin1 at the subscription level.

B: You can gradually roll out Seamless SSO to your users. You start by adding the following Azure AD URL to all or selected users' Intranet zone settings by using Group Policy in Active Directory: https://autologon.
microsoftazuread-sso.com
E: Seamless SSO works with any method of cloud authentication - Password Hash Synchronization or Pass- through Authentication, and can be enabled via Azure AD Connect.
References:
https://docs.microsoft.com/en-us/azure/active-directory/hybrid/how-to-connect-sso-quick-start