Scientists apply the concept of a molecular clock to estimate the time to species evolved separately. Which data are most useful for the estimation?
A. Common traits of the two species
B. Homologies among the two species
C. DNA sequence differences between the two species
D. DNA fingerprinting of common fossils

DNA sequence differences between the two species is the most useful data used by the scientist for the estimation of the molecular clock.

Explanation:

It is a figurative term used for determining the mutation rate and to deduce the time in the prehistory when two or more lives diverged.  It has granted paleontologists to reveal the story of the evolution over millions of years. If there is any change in the molecular clock it is termed as molecular evolution. If a clock is said to be the good molecular clock only when it contains the evolution of different genes at different rates which helps us to evolve the prehistoric period completely.

Ithink option a is correct because you cannot donate a different blood group than yours because it won't match.option a says betsy can donate to mark. they have the same blood group so donation can happen.