$x=3$, $y=2$, $z=7.$ 
Which of the following is correct?  $72=2^{x}\times3^{y}$  $539=z^{2}\times11$ 
Options:
a. $x\textgreater y\textgreater z$ 
b. $y\textgreater z\textgreater x$ 
c. $x\textgreater y=z$ 
d. $z\textgreater y\textgreater x$ 
e. $z\textgreater x\textgreater y$ 