求助一道kaplan的模考题

How many different ways can 2 students be seated in a row of 4 desks, so that there is always at least one empty desk between the students?
A. 2
B. 3
C. 4
D. 6
E. 12

给的答案是D，解释：
A common mistake is to pick (A). It's a logic task that many people prefer to visualize, using dashes for desks. We'll just refer to the desks as 1, 2, 3, and 4, in that order, and we'll call the students X and Y. In order to keep at least one empty desk between the two, we have to keep either one or two empty desks between them. If we keep only one desk between the two, there are two ways the chairs can be occupied: X can be in 1 with Y in 3, Y can be in 1 with X in 3, or X can be in 2 with Y in 4, or Y can be 2 with X in 4. If, on the other hand, we keep two empty chairs between the students, then there are two ways to occupy the desks: X can be in 1 withY in 4, or Y can be in 1 with X in 4. So there are 6 different possible arrangements

但是我觉得答案是8啊。
X和Y还可以在2,3，这样他们旁边也各有一个空位啊，对不？