Final answer:
The greatest likelihood of an acute hemolytic reaction in blood transfusion occurs when the recipient receives blood with ABO antigens incompatible with their antibodies, such as type B blood being given type A blood.
Step-by-step explanation:
A well-informed new graduate would know the greatest likelihood of an acute hemolytic reaction would occur when giving blood from a donor with antigens that are incompatible with the antibodies present in the recipient's plasma. For instance, if a patient with type B blood, which contains anti-A antibodies, is mistakenly given type A blood, the recipient's anti-A antibodies will bind to the donor's A antigens, causing the red blood cells to agglutinate and leading to a possible acute hemolytic transfusion reaction. Such acute hemolytic reactions are dangerous and can result in severe complications, including kidney failure, shock, and even death.