https://docs.microsoft.com/en-us/microsoft-365/admin/add-users/about-admin-roles?view=o365-worldwide

According to the Microsoft documentation1, you can use the Teams usage report in the Microsoft Teams admin center to get an overview of the usage activity in Teams. This includes the number of active users, channels, guests, and post messages via chat and conversations to know how many users in each team are actively using Teams to communicate and collaborate. However, this report only shows the last 7 or 28 days of activity of teams, which may not be enough to identify inactive teams over a longer period.
Alternatively, you can use PowerShell scripts to generate activity reports that check the audit records of inactive teams and provide an HTML report file based on SharePoint site activity in the group's document library in the past 90 days and conversations that occurred in the mailbox in the past year2. However, this method requires writing complex and time-consuming PowerShell commands, which may not be feasible for administrators who need to produce multiple reports on a daily basis.
Another method to detect inactive teams in your Teams environment is by setting an expiration policy for the associated group in Azure AD. This notifies the owner of the team or group by sending an email to renew or delete the team after specified days if no activity is detected3. However, this method also has some drawbacks, such as:
The owner may fail to notice the email or renew the team within the timeline of the configured policy, resulting in the team being deleted automatically and not being restorable after 30 days.
The expiration policy applies to all Microsoft 365 groups in an Azure AD organization, not just Teams. This may affect other groups that are not related to Teams.
The expiration policy requires Azure AD Premium licenses for the members of all groups to which the policy is applied.
Therefore, based on this information, the correct answer is D. the Teams usage report. This report is the most straightforward and accessible way to find inactive teams in Microsoft Teams, even though it has some limitations. The other options are either not related to finding inactive teams (Teams advisor) or require additional licenses or permissions (the Office 365 Groups activity report and the Teams user activity report).

Reference:
https://docs.microsoft.com/en-us/microsoftteams/qos-in-teams
https://docs.microsoft.com/en-us/microsoftteams/meeting-settings-in-teams

Reference:
https://docs.microsoft.com/en-us/microsoftteams/teams-client-update
https://docs.microsoft.com/en-us/microsoftteams/teams-for-vdi#install-teams-on-vdi

Reference:
https://docs.microsoft.com/en-us/microsoftteams/teams-and-skypeforbusiness-coexistence-and-interoperability