The answer to this is D. There are moments when this should be thoroughly checked especially if it would be used for those who would get donors. For example, one person might be getting a kidney and it would seem that they are a good match but through testing, it would show that the two antigens do not match.
The more that the antigens are not matching with each other, the higher the risk of placing that organ in a person. The body will most likely reject and attack the organ. It may end up with the organ not functioning as well as it should.