Identify the best way to determine if two organisms are closely related

The best way is to compare the DNA of the two species. The more nitrogenous bases and amino acids two species have in common, the more closely related they are.

dogs is better and probably lizards.

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.