21. What is the correct structure for 7-methyl-4-octanone? A) D) IV 22. What is the IUPAC name for the following compound? A) 5,5-dimethyl-2-heptanone B) 5,5-dimethylcycloheptanone C) 4,4-dimethylcycloheptanone D) 3,3-dimethylcycloheptanone E) none of these 23. What is the IUPAC name for the following compound? A) 4-benzylbutanal B) 3-phenylpropanal C) 3-benzylpropanal D) 4-phenylbutanal E) none of these