Based on the provided options, the correct answer is 4: AB or B.
To understand why this answer is correct, it is essential to have a basic understanding of blood types. Blood type is determined by the presence or absence of certain antigens on the surface of red blood cells. There are four main blood types: A, B, AB, and O.
An individual with blood type B has the B antigen on their red blood cells. This means that their blood contains antibodies against the A antigen. In an emergency situation, it is crucial to make sure that the donated blood does not react with the recipient`s blood, causing adverse reactions.
According to the rules of blood transfusion compatibility, individuals with blood type B can safely donate to individuals with blood types B or AB.
In option 4, it is stated that an individual with blood type B can donate blood to a person with blood type AB, which is correct. This is because blood type AB does not have antibodies against either the A or B antigens, making it the universal recipient. However, it is also stated that blood type B can donate to blood type B, which might seem redundant, but in an emergency situation, this ensures that there`s a compatible blood option available.