Metal 'X' displaces metal 'Y' from its salt solution but is not able to displace metal 'Z' from its salt solution. Identify the most reactive metal.

In the reactivity series, a more reactive metal displaces a less reactive metal from its salt solution. Since X displaces Y, X is more reactive than Y. Since X cannot displace Z, Z is more reactive than X. Therefore the order of reactivity is Z > X > Y, making Z the most reactive metal.