Which blood transfusion is correct ?

All the following options regarding blood transfusion is incorrect, except

All the following options regarding blood transfusion is incorrect, except

Which one among the following statements about blood transfusion is correct? Blood group B can give blood to

A certain road accident partient with unknown blood group needs immediate blood transfusion. His one doctor friend at once offers his blood. What was the blood group of the donor ?

A certain road accident patient with unknown blood group needs immediate blood transfusion. His one doctor friend at once offers his blood. What was the blood group of the donor?

In a certain road accident, patient with unknown blood group needs immediate blood transfusion. His one doctor friend at once offers his blood. What was the blood group of the donor ?

A certain road accident patient with unknown blood group needs immediate blood transfusion. His one doctor friend at once offers his blood. What was the blood group of the donor?