Reason from first principles: in civil law the person who alleges a wrong must prove it. The patient is the one alleging that the doctor was negligent, so the patient carries the burden of proof. Eliminate the distractors fast: a magistrate and a police sub-inspector are figures from criminal procedure, not parties who carry a civil burden of proof, so options 1 and 2 are out. The doctor is presumed innocent, so the burden does not start with the doctor, ruling out option 3. That leaves the patient. The one nuance worth remembering is res ipsa loquitur, where the negligence is self-evident and the burden then shifts onto the doctor, but the default rule for civil negligence keeps the onus on the patient. Correct answer: patient.