 Okay, so let's try this one, hopefully this one is a little easier for us. Which one of the following groups has the highest priority? So remember how we do priority, we, how do we do priority? We look at the what? Size of the atom. Or the atomic weight. Atomic weight, okay, because of course size and atomic weight don't all this correlate, okay? So what we're, when we see a problem like this, what we're saying is that whatever this is attached to, okay, this is the group, okay, this is the group, this is the group, this is the group. So if we look at all of these, right, the first atom is carbon in all of them, so that carbon atom doesn't distinguish which one has the highest priority, okay? From there, can anyone tell me which ones that they can cross out immediately because they see that there's an atom that is a lower atomic weight than another atom? B, okay, so why could we cancel out B? Because there's only a hydrogen. Because there's only a hydrogen, and in all the other ones, what do we have there? Oxygen, oxygen, oxygen, but wait a second, we have an oxygen here and a methylene group there, okay? So there is a question about the prioritization of those two, but I guess what we're saying is these two, we can essentially say are higher in priority than both of the other ones, right? Okay. So we're going to cancel that one out because of the hydrogen. Then why do we cancel this one out? Because it's a two level oxygen group. Because of that same CH2 group, right? Because when we're comparing that, that's an oxygen, that's an oxygen, and carbon is smaller than oxygen, or a weight less, right? Okay, so now we've got between A and C. So if we look, we've got carbon, double bond oxygen, oxygen. Carbon, double bond oxygen, oxygen. The only difference is methyl group, hydrogen, right? Which ones higher in priority? Okay. Yeah, so A or C? A. Okay, that's how you do it. So B is lower than D? B is lower than D. So when we're looking at this, right? Well, the double bonded oxygen is higher in priority than a single bonded oxygen? Sure. Okay. So this would be higher in priority than this one. Okay. Okay. Because this one's like attached, you can think of it as attached to two oxygens. It's the way you really want to think of it, like there's an oxygen there and an oxygen there, okay? This one's only attached to one oxygen. Here you can think of, okay, if I wanted to do that same analysis, it's attached to a carbon and a carbon like that, okay? So that's definitely not higher in priority than this one. Okay. Okay. If we had gotten all the way to the hydrogen, the carbon, and if we were comparing that, it would be a different story. That makes sense to you? Okay. Any other questions? That's a good question. Any other questions? Okay. Wonderful.