What is the correct decreasing order of reactivity of the metals X, Y and Z based on the following equations?

$$\begin{array}{*{20}{l}} {{\text{XCl}} + {\text{Y}} \to {\text{YCl}} + {\text{X}}} \\ {{\text{YCl}} + {\text{Z}} \to {\text{YCl}} + {\text{Z}}} \\ {{\text{ZCl}} + {\text{X}} \to {\text{XCl}} + {\text{Z}}} \end{array}$$

A.     X $>$ Y $>$ Z

B.     Y $>$ Z $>$ X

C.     Z $>$ Y $>$ X

D.     Y $>$ X $>$ Z

D

The two G2 comments on this question both stated that it would have been better if no reaction was given for the second equation, instead of repeating ${\text{YCl}} + {\text{Z}}$ as the products. This is a valid comment. The question however was generally well answered and 69% got the correct answer, D.