Examine the twelve structural formulas shown at the bottom of this page, and select those that satisfy each of the following conditions. Enter one or more letters ( A through L ) in each answer box, reflecting your choice for each. 
Do not enter superfluous characters, since they will be counted as incorrect answers.
| A  | B  | C  | D  | E  | F  | 
| G  | H  | I  | J  | K  | L  |