Answer: Of the four suspects, JOHN is the person of interest
Step-by-step explanation:
Since the blood collected from the crime scene was TYPE O, and TYPE O blood DO NOT react to either BLOOD TYPE A or B due to the fact that:
- it do not have antigen A
- it do not have antigen B
JOHN'S BLOOD type is the SAME as that collected from the crime scene. Thus, of the four suspects, JOHN is the person of interest