Ans. 'O' blood group.
Blood groups are classified on the basis of presence or absence of antigens and antibodies present in surface of RBCs (red blood cells). The blood type, which lacks both A and B antigens, but has both anti-A and anti-B antibodies represents 'O' blood group.
As sample red blood cell has no antigens, but contain antibodies A and B, the type of the blood sample is 'O.'