A simplified model of the human blood-type system has 4 blood types: A,B,AB and O. There are 2 antigens, anti-A and anti-B, that react with a person’s blood type. Anti-A reacts with blood types A and AB, but not with B and O. Anti-B reacts with blood types B and AB, but not with A and O. Suppose that a person’s blood is sampled and tested with the two antigens. Let D be the event that the blood reacts with anti-A, and let E be the event that the blood reacts with anti-B. Classify the person’s blood type using the events D, E, and their complements.

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