Jack follows the steps below. Step 1: He clicks the Design tab on the ribbon.
Step 2: He navigates to the Document Formatting command group.
Step 3: He clicks the Themes icon.
Step 4: He clicks the Office Theme option in the themes gallery.

Which task is Jack trying to do?
A. He is sharing the Office theme with others.
B. He is creating a new theme for his document.
C. He is saving an existing theme to the themes gallery.
D. He is applying an existing theme to his document.