How does propagation occur in DNA and RNA?

Life on earth is very diverse, from single-celled protozoans to complex multicellular plants and animals. But at the molecular level, all life is fundamentally made up of the same building blocks – DNA and RNA. One of the primary differences between DNA and RNA is that DNA is double-stranded while RNA is single-stranded.

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.