Answer:
Contextual tabs
Step-by-step explanation:
A ribbon is a command bar that organizes different features in tabs at the top of the window to help people find commands easily. A ribbon has tabs that are always displayed that are called core tabs and tabs that are only showed when an object type is selected and they are called contextual tabs. So, according to this, the name of the special tab that appears on the Ribbon when part of the document is selected is contextual tabs.