Which of these statements is true? a. An antibiotic is any substance produced by a prokaryote that is antagonistic to the growth of other viruses. b. An antibiotic is any substance produced by a organism that is antagonistic to the growth of prokaryotes. c. An antibiotic is any substance produced by a prokaryote that is antagonistic to the growth of eukaryotic cells. d. An antibiotic is any substance produced by a prokaryote that prevents growth of the same prokaryote.