The correct answer is D. Ctrl + Shift + B.
The bookmarks bar is a toolbar that displays your bookmarks. It is located at the top of the browser window, below the address bar. To show or hide the bookmarks bar, you can use the keyboard shortcut Ctrl + Shift + B.
Option A, Alt + Ctrl + K, is not a valid keyboard shortcut for showing or hiding the bookmarks bar in Google Chrome.
Option B, Ctrl + Shift + C, is the keyboard shortcut for copying text.
Option C, Ctrl + Shift + K, is the keyboard shortcut for opening the keyboard shortcuts menu.
I hope this helps!