In Medical Cases, Which of the Following Causation Rules Will

In medical cases, which of the following causation rules will apply?

A) The immediate medical cause of resulting harm will be regarded as the legal cause.
B) D's act does not need to be the sole cause provided it contributed significantly to the result or was a substantial and operating cause
C) The fact that V dies because of negligent medical treatment for an initial injury will excuse D of responsibility for death because it is voluntary and unforeseeable.
D) Before medical negligence will break the chain of causation it must be abnormal and independent which is a question of law.