How are transesterification reactions catalyzed by tertiary amines?

• A. The 3° amine stabilizes the tetrahedral intermediate, making the elimination of the alkoxide group of the starting ester more likely.
• B. An acid-base reaction occurs between the 3° amine and alcohol, forming an alkoxide ion that is a stronger nucleophile.
• C. The 3° amine forms a complex with the carbonyl group, making it more susceptible to a nucleophilic attack from an alcohol.
• D. Nucleophilic attack by the 3° amine forms a positively-charged amide that is more reactive than the starting ester.

Answer: (D)