Which serves as evidence for a scientific claim?

      For this question, you need to pay attention and understand all the process of the scientific methodology, and how it works.

       First of all, to have a scientific claim, we need to have the observation, you need to see it happening, taking notes of it, and then we can really start the job. After the observation, we need to check again if that's what is really happening, so you're going to do the same process all over again.

        After that, you're sure of your notes, and now we can start sharing thoughts with other scientists to stablish some hypothesis of what's happening or what will happen if I do something specific, remember, the hypothesis needs to be verified, you need to have a way to check how that can be true and false, and by that, if what happens match with your hypothesis, you need an explanation for that. After stablishing this explanation and checking it several times, that can be said it's a scientific theory.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.