Answer
O-
Work Step by Step
In the provided Venn diagram, it contains eight region representing the eight common blood groups. There are three antigens A, B and Rh. So the blood with Rh antigen is labeled positive and lacking Rh antigen labeled negative.
According to this information, the required sets are:
\[\begin{align}
& U=\left\{ {{\text{A}}^{+}},{{\text{A}}^{-}},A{{B}^{+}},A{{B}^{-}},{{B}^{+}},{{B}^{-}},{{O}^{+}},{{O}^{-}} \right\} \\
& A=\left\{ {{\text{A}}^{+}}\text{,}{{\text{A}}^{-}}\text{,A}{{\text{B}}^{+}}\text{,A}{{\text{B}}^{-}} \right\} \\
& B=\left\{ \text{A}{{\text{B}}^{+}}\text{,A}{{\text{B}}^{-}}\text{,}{{\text{B}}^{+}}\text{,}{{\text{B}}^{-}} \right\} \\
& C=\left\{ {{\text{A}}^{+}}\text{,A}{{\text{B}}^{+}}\text{,}{{\text{B}}^{+}}\text{,}{{\text{O}}^{+}} \right\}
\end{align}\]
So, in the innermost region V, the blood group \[\text{A}{{\text{B}}^{+}}\]indicating that the person having that blood group type has antigens A, B and Rh. Blood type O(both positive and negative) lacks antigens A and B.
Type \[{{\text{O}}^{+}}\]has antigen Rh only. But blood type \[{{\text{O}}^{-}}\] lacks all three antigens A, B and Rh.
In the blood transfusion, the recipient must have all or more of the antigens present in the donor’s blood.
Since blood group \[{{\text{O}}^{-}}\]lacks of all the three antigens. So, the person whose blood group is \[{{\text{O}}^{-}}\]can donate blood to all other blood types. Therefore, it is a universal donor (who can donate blood of all the blood types).
