Given the task definition and input, reply with output. In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".

[header] How to add toolbars to your browsers [title] Launch firefox. [step] Double-click on the browser's shortcut icon on your desktop to launch it. [title] Open the menu. <sep> (A) [step] On most browsers, scroll down and select firefox on the menu panel. You will see many options, such as split-screen or full screen. (B) [step] Locate the " search engines " folder on your bottom toolbar, and click on it. The menu panel should expand on-screen and show a list of search engines that you can browse. (C) [step] It's the green gears icon typically found on a lower-right corner of the browser window, typically located on the dock or inside of the left panel. This displays a menu that lists settings for your running programs. (D) [step] Click the menu button at the upper-right corner of the browser window, which is an icon of three rows stacked upon each other. This will open the menu where you can customize your firefox browsing experience.
D