Which one of these words should not be used in the comparative or superlative degree? a. wealthy b. sweet c. smart d. absolute

The word that should not be used in the comparative or superlative degree is D. absolute. The word absolute is already at the highest degree possible - nothing can be more or less absolute than something else, because it is already complete and perfect. You cannot say - It is the most absolute of all - because that would mean all things are absolute, which obviously is not true. Wealthy, smart, and sweet do have comparative and superlative degrees, but absolute doesn't.