Step 1: Concept Nucleophilic acyl substitution reactivity depends on the leaving group ability and the electrophilicity of the carbonyl carbon.
Step 2: Meaning A better leaving group (weaker base) makes the derivative more reactive.
Step 3: Analysis Chloride ($Cl^{-}$) is the best leaving group, making acid chlorides (A) most reactive. Carboxylate is next (B), followed by alkoxide (C). Amide ($NH_{2}^{-}$) is the poorest leaving group, making amides (D) the least reactive.
Step 4: Conclusion The reactivity order is: Acid Chloride $>$ Acid Anhydride $>$ Ester $>$ Acid $>$ Amide, which is A $>$ B $>$ C $>$ E $>$ D.
Final Answer: (D)