B

Linezolid blocks the initiation of protein synthesis by binding to the 50 S ribosomal subunit and has no action on DNA replication or repair [Champney & Miller, 2002, PMID 11927986]. In contrast, rifampicin inhibits DNA-dependent RNA polymerase (affecting transcription) [McClure & Cech, 1978, PMID 363713], while nitrofurantoin and metronidazole are reduced inside bacteria to reactive species that directly damage or fragment DNA [McOsker & Fitzpatrick, 1994, PMID 7928834; Edwards, 1980, PMID 7000306]. Thus, among the listed drugs only linezolid does not interfere with DNA synthesis.