which issue is related to long-term heroin use?\n○ pleasure\n○ depression\n○ hypoxia\n○ mood swings

Brief Explanations:

Long - term heroin use can disrupt the body's oxygen supply mechanisms. Hypoxia is a condition where there is a deficiency in the amount of oxygen reaching the tissues. Heroin can affect the respiratory system, leading to decreased oxygen intake and subsequent hypoxia. Pleasure is a short - term effect of heroin use, not a long - term issue related to its use. Depression and mood swings, while possible in some cases, are not as directly related to the physiological impact of long - term heroin use on oxygen levels as hypoxia is.

Answer:

C. hypoxia