The father could be:
A.	A, AB, B, or O Dr. Hallick's reply: Unfortunately for this particular case, one cannot distinguish between any potential fathers from blood type alone. Note from the table that a mother with type A blood could have created a child with type A blood with a father of any of the four possible blood types, typeA, type AB, type B, or type O. Likewise, the father of the child could be either Rh+ or Rh-. It should be apparent from this discussion that blood type is not a very good test for paternity. In some cases, unambigous information can be obtained, i.e. a type AB male cannot father a type O child. However in most cases, the results are uncertain. If determining the paternity of a child is important, there are very sensitive DNA test currently available that can establish paternity to a certainty in excess of 99.99%, or exclude someone as the biological father with absolute certainty. Elsewhere in the Biology Project is an excercise to follow the inheritance of DNA markers in a paternity study.
B.	Either A or B
C.	Either A or O