What is the definition of Stabilizing selection, directional selection and disruptive selection (make your sentence short and in your OWN words)

Stabilizing selection is a type of natural selection in which the population mean stabilizes on a particular non-extreme trait value.

directional selection is a mode of natural selection is  an extreme phenotype is favored over other phenotypes.

Disruptive selection describes changes in population genetics in which extreme values for a trait are favored over intermediate values.

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.