27. Choose the endo product for the following reaction:

25. What starting materials would be suitable for preparing this compound by a combination of Michael and aldol reactions? (A) 4-methyl-2-cyclohexen-1-one and 3-butenal (B) 2-methylcyclohexane-1,3-dione and 3-buten-2-one (C) 2-methyl-2-vinyl-3-cyclohexen-1-one and acetaldehyde (D) 2-methyl-2-cyclohexen-1-one and 1,4-dichlorobutan-2-one (E) 4-methylcyclohexnone and methyl vinyl ketone