The Options menu is effectively a dumping ground for menu items that don't belong in any of the other menus; the following items have been abandoned here:
Enable or disable anti-aliasing within Ghostscript. Your copy of Ghostscript must support the x11alpha device if you want to use anti-aliasing. Note that anti-aliasing can make some PostScript files look worse (see Caveats and Bugs).
Enable or disable magic scrolling. When magic scrolling is enabled, attempting to scroll down at the bottom of a page (or scroll up at the top of a page) will move you to the next (or previous) page. The magicResistance resource controls the number of attempts you have to make before magic scrolling takes effect.
Enable or disable smooth scrolling. When smooth scrolling is enabled, scrolling with the mgvScroll action (i.e. with the arrow keys but not the little buttons on the scrollbars) will scroll the screen a couple pixels at a time with an update after each movement; this will give the scrolling a smoother appearance than the normal scrolling. When smooth scrolling is disabled, normal scrolling is performed. The smoothScrolling resource controls the initial state of smooth scrolling and the smoothness resource controls how smooth the scrolling will be. If you're interested in the scrolling, you might want to look at the scrollPercentage resource as well.
Enable or disable smart sizing. The documentation for the smartSizing resource covers the smart sizing features and their limitations. Note that smart sizing places upper limits on the main window size whereas automatic sizing places lower limits on the main window size.
This sub-menu allows you to choose the color palette used for rendering files. You can choose from Monochrome, Grayscale, and Color palettes. Palette changes are not propagated to existing zoom windows but the new palette will be used by new zoom windows.