The correct answer is option 4, AB+. This blood group is known as the universal acceptor because individuals with AB+ blood can receive blood from donors of any blood type. This is possible because the AB+ blood type has both A and B antigens on its red blood cells, as well as the Rh antigen. This means that individuals with AB+ blood do not produce antibodies against A, B, or Rh antigens, allowing them to safely receive blood from donors with any blood type.

Options 1 and 2, 0+ and O-, respectively, are not universal acceptors. O- is known as the universal donor because it lacks A, B, and Rh antigens, making it compatible with any blood type. However, O- individuals can only receive O- blood. Option 3, AB-, can receive blood from donors with AB- and O- blood types, but not from donors with A, B, or O+ blood types.