Which of the following is a TRUE statement about the effects of STIs on one's health?

Some STIs can affect more than the reproductive organs. For example, untreated syphilis can damage the brain and nervous system and cause serious mental or neurological problems, so statement A is true. Statement B is false because some STIs can cause effects throughout the body, and having no symptoms does not make blood donation safe; statement C is false for the same reason. Therefore, “all of the above” is not correct.

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