Why Are People More Likely to Die from Overdoses of Opiates

Why are people more likely to die from overdoses of opiates than from overdoses of marijuana?

A) There are more opiate receptors in the brain than THC receptors.
B) People generally begin abusing opiates at a younger age than they do marijuana.
C) Opiate receptors are more prevalent in areas of the brain that control heart rate and breathing.
D) Opiates dissolve in the fats of the body; marijuana does not.