How can I do this? Why is it not A?
(I may not be correct, so feel free to educate me on this!)
But from the question I figured it is implied that the more differences in the Cytochrome-C amino acids between species, the longer/'more apart' two species have evolved from each other?
Between species A and species B, there are the MOST differences in amino acids (11) out of the three species - meaning they are the least related to each other out of the three.
Whereas, between species A and species C, there are the LEAST differences in amino acids (3) - meaning they are the most related to each other out of the three (shorter time since they have evolved from each other).
Between species B and species C, there are 10 differences in amino acids, meaning they evolved from each other probably around the same time species A and species B evolved from each other.
Hence, I would say (B) is the correct answer? Mainly because the branch between species A and species C is relatively the 'shortest'. (Branch length represents the length of time two species have evolved from each other, longer branch = longer time // shorter branch = shorter time)
Hehe, don't know if that made sense, but hope that helped and I need to get stuck into revising this more as well, so thanks for the reminder.