Ans: C. CarbapenemsNew Delhi metallo-beta-lactamase f (NDM-f ):An enzyme that makes bacteria resistant to a broad range of beta-lactam antibiotics.These include the antibiotics of the carbapenem family, which are a mainstay for the treatment of antibiotic-resistant bacterial infections.The gene for NDM- I is one member of a large gene family that encodes beta-lactamase enzymes called carbapenemases.Bacteria that produce carbapenemases are often referred to in the news media as "superbugs".Because infections caused by them are difficult to treat.Such bacteria are usually susceptible only to polymyxins and tigecycline.