The correct option is D Fratricide
'Murder of a brother' is Option D, Fratricide. Option A, 'Patricide' is killing of one's father. Option B, 'Regicide' is action of killing a king . Option C, 'Homicide' is killing of one person by another. Thus, options A, B and C are incorrect and the correct word for the given phrase is Option D, Fratricide.