The acquisition of drug resistance is described as what type of response?

The acquisition of drug resistance is best described as an adaptive response. This occurs when organisms, such as bacteria, evolve and acquire new traits that enable them to survive in the presence of drugs that would normally inhibit or kill them. Over time, through processes such as natural selection and genetic mutations, these organisms adapt to their environment, developing mechanisms that allow them to tolerate or resist the effects of drugs.

An adaptive response reflects the dynamic nature of biological systems where changes occur in response to environmental pressures, in this case, the presence of drugs. This process can involve the upregulation of efflux pumps that remove the drug from the cell, alterations in the drug's target site, or the acquisition of new resistance genes through horizontal gene transfer.

The other responses, while related to biological reactions, do not accurately describe the process of acquiring drug resistance. The immune response specifically refers to the body's defense mechanisms against pathogens rather than adaptation to drugs. A tolerant response generally indicates the ability to withstand a substance without necessarily evolving resistance, and a reactive response implies a direct reaction to a stimulus rather than a more gradual evolutionary change.