Which of the following is useful for providing a list of off-screen navigation items when you swipe to the right or left?

a. A horizontal scroll bar
b. A vertical scroll bar
c. A DrawerLayout
d. A LinearLayout

c. A DrawerLayout
A DrawerLayout is especially useful for providing a list of navigation items that are hidden off the screen but presented when users swipe from the left or the right, or when they press the Home button from the action bar if the DrawerLayout resides to the left.
DrawerLayout should really be used only for navigation and only when there are more than three top-level views within your application.