Alright. So here we have an example problem that wants us to fill in the 2 blanks here in this sentence using one of these 4 potential answer options down below. And the example problem says, according to the diagram over here, A is blank, whereas B is blank. And so when we take a look at this diagram over here, notice that on one end what we have is A, and on the opposite end of the diagram, what we have are the 3 domains of life: domain bacteria, archaea, and eukarya. And so, notice that A is right here at this position and B is specifically pointing to this position right here. And so when we take a look at option A here it says, that A is the most recent species to evolve on Earth. But, of course, we know from our last lesson video that when we see a diagram like this one, that it's actually based on time and, furthest to the right, what we have is the present. So this represents the present. And, as you go backwards, we're actually going into the past. And so, the three domains of life are what we have in today's present world. However, going backwards into the past, this is where we started. And so what we're saying is that, A, by saying that it is the most recent species to evolve on Earth, it's not really recent at all if it's way back in the past. A is in the past and, the most recent species to evolve are going to be in the present, somewhere towards the right of the diagram. And so what that means is we can eliminate answer option A and answer option B since both of them say that for this first blank A is the most recent species to evolve on Earth, and we know that's not right. Instead, we know that A is going to be the common ancestor of all life, so it's either going to be option C or option D. That's the correct answer for this problem. And since both C and D have the same thing for the first blank, we need to take a look at what it says for option B. So, B is, this option here says, the common ancestor of bacteria and archaea. And, this option here says that B is the last common ancestor of archaea and eukarya. And so when we take a look at B, again, it's pointing to this specific location right here. And so, this is referring to the closest relationship between archaea and eukarya. The closest relationship between archaea and bacteria would be up here. So if you were to trace this back, this is the closest place that they meet. And so, what that means is we can eliminate answer option C because it says that B is, the common ancestor of bacteria and archaea, but that's not true of B. That would actually be up here. And so that only leaves answer option D here as the correct answer. And so, B is going to be the last common ancestor of archaea and eukarya. That's where they connect most recently right here. And so D here is going to be the correct answer for this example problem, and that concludes this example solve. See you guys in our next video.