Assume that you work in criminal investigation unit and were called for an incident that involved someone who was shot. you arrived to the scene to see a dead person in his 50s and no other evidences rather than a small piece of clothing with blood on it. you collected the blood and went to the lab. the investigation lead to four suspects that happened to be either close to the place of incident or had problems with the victim. you checked the blood type of that blood and it was (o). when you did blood typing for the four suspects, the results came out as the followings: jacks blood reacted only to a, sams blood reacted to both a and b, nathans blood reacted only to b, and johns blood didnt react to either a or b. which one of the four is the person of interest (suspect) based on the blood typing reaction?