HFDB: GEC ⇒ A B C D E F G H I. In this you can see that G, E, C is in the middle of HF, FD and DB, respectively. Similarly, YWUS: XVT ⇒ S T U V W X Y. In this you can see that X, V, T is located in the middle of YW, WU and US, respectively. This type of relationship is not made in other options. So the correct answer would be XVT.