Compared to older tetracyclines, doxycycline produces a lower incidence of superinfection diarrhoea because (a) It is completely absorbed in the small intestines so that drug concentration in the colonic contents is low (b) It is inactivated by the gut microflora (c) It is not active against the microbes of the normal gut flora (d) It is a potent tetracycline and inhibits the superinfection causing microbes as well