If the double bond is broken heterolytically, formal charge pairs result, as shown in the other two structures. The preferred charge distribution will have the positive charge on the less electronegative atom (carbon) and the negative charge on the more electronegative atom (oxygen).
Single malt Scotch. Single malt Scotch is single malt whisky made in Scotland. To be a single malt scotch the whisky must have been distilled at a single distillery using a pot still distillation process and made from a mash of malted grain. In Scotland, the only grain allowed to be used in a single malt whisky is barley.
In other words, single malt scotch comes from a single location where the grain mash was fermented, distilled, and aged. You won't really find double malt scotch anywhere, but you will find blended malt scotch, which means the scotch you are drinking is a blend of different single malt scotches. Check out this website for more info on the differences between whiskey types.