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

See the solution in the explanation below:
Explanation:
To configure a virtual receptionist for your company's main office, you can use the Teams admin center to create and assign an auto attendant. An auto attendant is a voice menu system that allows callers to be transferred to an extension or a queue without speaking to an operator or receptionist. Here are the steps to create and assign an auto attendant that meets your requirements:
* Sign in to the Teams admin center with your Microsoft 365 username and password.
* In the left navigation, go to Voice > Auto attendants.
* Click Add (+) to create a new auto attendant.
* In the Basics tab, enter a name and an optional description for the auto attendant, such as "Main Office Receptionist".
* Under Phone number, select Assign and then choose a service number from the list or click Add new number to get a new one. A service number is a type of phone number that can handle hundreds of simultaneous calls and is used for services such as audio conferencing, auto attendants, and call queues.
* Click Apply and then Next.
* In the Greeting and menu tab, under Greeting, select Custom and then click Upload audio file to upload a recorded greeting message for the callers, such as "Welcome to Microsoft. Please listen carefully to the following options."
* Under Menu options, click Add (+) and then select Key press from the drop-down menu.
* In the Key press box, enter 1 and then select Dial by name from the Action drop-down menu. This will allow callers to press 1 for the company directory to lookup by name.
* Click Add (+) again and then select Key press from the drop-down menu.
* In the Key press box, enter 0 and then select Play audio file from the Action drop-down menu. This will allow callers to press 0 to hear the company address.
* Click Upload audio file and then upload a recorded message with the company address, such as "Our main office is located at 1 Microsoft Way, Redmond."
* Under Menu options, turn on the toggle for Repeat menu until caller hangs up or presses #. This will offer the same menu at all times.
* Click Next.
* In the Business hours tab, under Business hours, select 24/7 from the drop-down menu. This will make the auto attendant available at all times.
* Click Next.
* In the Review tab, review your settings and then click Save.
Now, you have configured a virtual receptionist for your company's main office that meets your requirements.

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).