The principle says whoever causes death by a rash or negligent act commits an offence. X ran a high voltage live wire along the fence at the back of his house to keep out intruders, and Z, who was simply passing through the public street behind the house and sat down to rest near the fence, died on touching it while getting up.
Because charging a fence next to a public street with lethal current is a rash and negligent act that led directly to a passerby's death, the facts match the offence the principle describes.
Therefore, the correct answer is X has committed an offence of causing death by rash and negligent act.
The fact that decides this question is where the fence was and who could reach it, a live high voltage wire along a boundary next to a public street, where Z, an ordinary passerby resting nearby, was fatally shocked. The principle is about rashness or negligence in causing death, so each option should be tested against that risk to the general public.
Testing each option against the risk the live fence posed to ordinary passersby on a public street leaves only the option finding a rash and negligent act.
Therefore, the correct answer is X has committed an offence of causing death by rash and negligent act.