Final answer:
The most common blood type in the Brandywine population is Type O (Type D) because it lacks both the A and B antigens, making it compatible with all blood types.
Step-by-step explanation:
In the Brandywine population, the most common blood type is Type O. This is because Type O blood lacks both the A and B antigens, making it compatible with all blood types.
Although it is not explicitly mentioned in the question, Type O can be considered as Type D in some blood typing systems. Therefore, Type D (Type O) is the most common blood type in the Brandywine population.