Ester Hydrolysis and Re-esterification Steps:

• Ethyl propanoate (CH₃CH₂C(O)OCH₂CH₃) undergoes basic hydrolysis with aqueous NaOH to yield sodium propanoate and ethanol (CH₃CH₂OH).
• The alcohol produced is ethanol.
• Ethanol reacts with propanoic acid (CH₃CH₂COOH) via esterification to form the ester CH₃CH₂C(O)OCH₂CH₃.
• This second ester is ethyl propanoate, matching option A.

Why A is correct:

• A depicts CH₃CH₂OC(O)CH₂CH₃, the formula for ethyl propanoate from esterification of ethanol and propanoic acid.

Why the others are wrong:

• B shows CH₃CH₂CH₂OC(O)CH₃ (propyl acetate), using propanol instead of ethanol.
• C shows CH₃C(O)OCH(CH₃)CH₃ (isopropyl acetate), using isopropanol and acetic acid.
• D shows CH₃CH₂C(O)OCH(CH₃)CH₃ (isopropyl propanoate), using isopropanol instead of ethanol.

Final answer: A