Which of the following statements concerning the cellular basis of disease are true? Check all that apply.

Foreign bacteria can harm human cells by invading them, releasing toxins, or triggering damaging immune responses, so B is true. Not all bacteria cause infections; many are harmless or beneficial, making A false. Most diseases involve cells that are damaged or not functioning properly, which supports C. Understanding what goes wrong in cells can help researchers develop treatments that target the cause of disease, so D is also true.

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