Explanation
Graphical user interface, text, application, chat or text message Description automatically generated

Box 1: Yes
As part of your app you can add custom tabs to embed your own web content in Teams, and using the Teams JavaScript client SDK, add Teams-specific functionality to your web content.
Box 2: Yes
You can use the Office JavaScript API to create task pane or content add-ins for Office 2013 host applications.
Box 3: Yes
You can use the Office JavaScript API to create task pane or content add-ins for Office 2013 host applications.
Reference: https://docs.microsoft.com/en-us/microsoftteams/platform/tabs/what-are-tabs
https://docs.microsoft.com/en-us/office/dev/add-ins/develop/support-for-task-pane-and-content-add-ins

Reference:
https://docs.microsoft.com/en-us/office/dev/add-ins/develop/support-for-task-pane-and-content-add-ins

Explanation
In the app manifest for your Microsoft Teams app you'll define a single messaging extension with up to ten different commands. Each command defines a type (action or search), and the locations in the client it can be invoked from (compose message area, command bar, and/or message).
Reference:
https://docs.microsoft.com/en-us/microsoftteams/platform/messaging-extensions/what-are-messaging-extensions