Question

read the passage and answer the following question(s).
pneumonia: a global threat
pneumonia is a lung infection that can be caused by several strains of bacteria. this type of infection can be treated with antibiotics, such as penicillin. it can also be prevented through vaccines for bacteria that can cause pneumonia. when antibiotics and vaccines were introduced, infections were greatly reduced; however, bacteria change to survive the antibiotics and vaccines. the most common change happens through mutations. the rate of mutations in pneumonia - causing bacteria occurs approximately once every 15 weeks. these mutations help bacteria develop resistance to antibiotics. the number of resistant bacteria then increases due to natural selection. the diagram shows a bacterial population that is treated with an antibiotic.
bacteria population that includes resistant bacterium
antibiotic is applied, bacteria without the resistant mutation die
the resistant bacterium multiplies and becomes more common
the entire infection evolves into a resistant strain
normal bacterium
dead bacterium
resistant bacterium
the overuse and misuse of antibiotics can also cause drug resistance. the overuse of antibiotics contributes to a faster rate of mutation, helping the bacteria to modify at a quicker rate. by the time newer vaccines or drugs are introduced, some bacteria have already developed resistance. misusing antibiotics, by not completing a prescribed course, contributes to the likelihood that more bacteria will become resistant.
resistant bacteria make it harder and more expensive to treat infections. this is a major threat to public health. one of the newer approaches to prevent the spread of disease is by providing adequate nutrition, sanitation, and addressing environmental factors. antibiotic treatment can achieve a better outcome when two or more drugs are combined during treatment. new drugs and vaccines are also being developed to prevent and treat future infections.
which best describes how bacteria achieve drug resistance?
through resistant genes
through decreased bacterial growth in the human body
through increased immunity in the human body

Explanation:

The passage states bacteria develop resistance mainly through mutations which help them develop resistance to antibiotics, and these mutations are related to genetic - level changes. Resistant genes are the key factor for bacteria to achieve drug resistance as they allow bacteria to survive the action of antibiotics.

Answer:

through resistant genes