Cho sơ đồ chuyển hóa:
A
$\xrightarrow[-N{{H}_{3}},-{{H}_{2}}O]{\text{dd},NaOH,{{t}^{o}}}$
B
$\xrightarrow[-N{{a}_{2}}S{{O}_{4}}]{{{H}_{2}}S{{O}_{4}}}$
C
$\xrightarrow[-{{H}_{2}}O]{{{C}_{2}}{{H}_{5}}OH,{{H}_{2}}S{{O}_{4}},{{t}^{o}}}$
CH3-CH(NH3HSO4)-COOC2H5
A là
A. CH3-CH(NH2)-COONH4
B. CH3-CH(CH3)-COONH4
C. H2N-CH2-CH2-COOH.
D. CH3-CH(NH2)-COOH.