Why Is a False Positive More Significant in HIV Testing

Why is a false positive more significant in HIV testing of patients than in screening donated blood for transfusions?

A) It isn't-both are equally dangerous/significant. False positives in PEOPLE can lead to psychological trauma, but false positives in BLOOD could lead to the useful blood being disposed.
B) A false positive in a PERSON is easily re-testable. This makes it more significant, because we would simply quickly retest the person to verify their actual HIV status.
C) A false positive in BLOOD is easily re-testable. This makes it less significant, because we would simply quickly retest the blood to verify its actual HIV status.
D) This statement is backwards-false positives in blood testing are more significant. If the false positive rate is high and we don't realize it, we're more likely to dispose useful blood. This could lead to acute shortages of blood for patients that need transfusions.