Which of the following best describes the primary molecular mechanism by which polymyxins (a class of lipopeptides) kill Gram-negative bacteria?

They electrostatically bind lipopolysaccharide on the outer membrane and insert hydrophobic tails into the bilayer to disrupt membrane integrity and cause leakage.

They are taken up by bacterial transporters and intercalate into ribosomes, blocking protein elongation in a way that is specific to bacterial ribosomal RNA structure and does not disrupt membranes directly.

They enzymatically cleave phospholipids on the inner membrane surface through a targeted lipase activity, generating fatty acids that dissolve the membrane bilayer.

They irreversibly inhibit peptidoglycan cross-linking by binding to penicillin-binding proteins and preventing cell wall synthesis, which subsequently causes osmotic lysis due to weakened walls.