The correct answer is: A. Separator line.
A separator line is a thin, horizontal line that is used to visually group together related items on a menu or submenu. It is typically used to separate different sections of a menu, such as the main menu items and the submenu items. Separator lines can also be used to separate individual menu items, such as when there are a large number of items on a menu.
Option B, “Separator bar”, is incorrect because a separator bar is a thicker, more prominent line that is used to separate different sections of a page or document. Option C, “Line”, is incorrect because a line can be used for a variety of purposes, such as to separate text or to indicate a boundary. Option D, “Bar”, is incorrect because a bar can be used for a variety of purposes, such as to indicate a button or to represent a quantity.