Aren't they all causes of death? What specifically does your text say?
Remember the difference between manner and cause of death.
B is correct, I believe
It's a matter of word usage. A coroner will list the manner of death (heart attack, suicide by hanging, strangulation, etc.) as the cause of death. All will result in lack of oxygen to the brain, which (in these cases) will be the actual cause of death.
Yes, "being strangled" would be considered a cause of death.
