The important substance for the special flavor of beef is ( ) in beef. A: Benzoic acid B: pyruvate C: fatty acid D: amino acid

吡罗昔康的化学名 A: 4-Butyl-1-(4-hydroxyphenyl)-2-phenyl-3， 5-pyrazolidinedione B: 2-[(2, 3-Dimethylphenyl)amino] benzoic acid C: 1-(4-Chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetic acid D: 4-Hydroxy-2-methyl-N-2-pyridinyl-2H-1， 2-benzothiazine-3-carboxamide 1,1-dioxide E: 4-[5-(4-Methylphenyl )-3-( trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfon amide