According to Carter's classification, Pasteurella multocida is differentiated into five capsular serogroups designated A, B, D, E, and F based on indirect hemagglutination / capsule chemistry (e.g., A = hyaluronic acid, B & E = hemorrhagic septicemia, D = heparin, F = chondroitin). Note that serogroup C does not exist.

Morphological and Gram-staining characteristics of Vibrio cholerae:

• Bacterial shape: The genus name Vibrio denotes curved, comma-shaped bacilli or short rods showing characteristic darting motility.
• Gram-staining color: Gram-negative bacteria have a thin peptidoglycan layer that loses crystal violet-iodine during alcohol/acetone decolorization and takes up the counterstain (safranin or basic fuchsin), appearing pink or red under light microscopy.
  
  Option breakdown:
• Spherical (coccus) shape is incorrect.
• Violet color denotes Gram-positive bacteria.
• Bacteria do not have conical shapes.
• Comma shape and pink color correctly describes Gram-negative Vibrio.

Penicillin is a prototypical $\beta$-lactam bactericidal antibiotic. Its mechanism of action involves:

• The structural similarity of the $\beta$-lactam ring to the D-alanyl-D-alanine terminus of peptidoglycan precursor pentapeptides.
• Irreversible binding and inhibition of transpeptidase enzymes (Penicillin-Binding Proteins, PBPs).
• Inhibition of the final cross-linking step of peptidoglycan chains during cell wall synthesis in actively multiplying bacteria.
• Activation of bacterial autolytic enzymes (autolysins), leading to osmotic lysis and death.
  
  Option breakdown:
• and (B) describe fluoroquinolones (inhibit DNA gyrase/topoisomerase IV).
• Inhibit peptidoglycan cell wall synthesis is the precise mechanism of penicillin.
• Penicillin has potent bactericidal action.