Final answer:
Vancomycin is a broad-spectrum antibiotic that inhibits cell wall biosynthesis in Gram-positive bacteria by binding to the end of the peptide chain of cell wall precursors.
Step-by-step explanation:
The correct answer to this question is A. Vancomycin.
Vancomycin is produced by Streptomyces and is a broad-spectrum antibiotic that inhibits cell wall biosynthesis in Gram-positive bacteria. It acts by binding to the end of the peptide chain of cell wall precursors, preventing their incorporation into the peptidoglycan structure. Vancomycin is bactericidal, meaning it kills bacteria.
Penicillin and cephalosporin are also cell wall synthesis inhibitors, but they are effective against Gram-positive bacteria only. Polymyxin B is an inhibitor of membrane function and disrupts the cytoplasmic membrane in Gram-negative bacteria.