Drug abuse can often lead to suicide because

a.
drugs can amplify preexisting negative emotions

b.
drugs negatively influence a person's ability to make good judgments

c.
withdrawal symptoms can be too overwhelming for the addict

d.
all of the above

D is the correct answer. Many drugs can target the parts of the brain that influence decision making and make the user's judgement and decision making less good. They can also make a negative situation seem worse than it is already. Additionally, withdrawal symptoms are emotionally and physically taxing so they can become overwhelming.