Problem Solving (PS) | A list of possible transplant patients contains people who can accept

Here's my 2 cents, I do not know if it'll help. This was a tricky question to think about, and I certainly hope it is not on the real GMAT!

Each group is its own subgroup and DO NOT overlap.


1. Only O: nothing else. They cannot accept any other blood.

2. A and O: Cannot accept B, so it cannot overlap with B or O (because they are unique).
--- What about only A? all of A can accept O

3. B and O: Cannot
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