74 下列何者是構成細胞壁 peptidoglycan 之主要成分？ (A) N-acetylglucosamine and N-acetylbutyric acid (B) N-acetylglucosamine and N-acetylmuramic acid (C) N-phosphoglucosamine and N-acetylbutyric acid (D) N-phosphoglucosamine and N-acetylmuramic acid