Some bacteria—sometimes called “super bugs”-have developed a resistance to
certain antibiotics. How does drug resistance develop in bacteria?
A. Unsanitary conditions allow all kinds of bacteria to breed, including those that
are antibiotic resistant.
B. In the bloodstream, different species of bacteria exchange genes and become
resistant to antibiotics.
C. Mutations in some bacterial genes make the bacteria stronger and better able to
defeat the body's immune system.
D. In the presence of an antibiotic, bacteria with genes that make them resistant
survive and eventually take over the population.