Find all the free variables this wff

$($

that is

$,$

$$free occurrences of a variable

$)$

:

ExEyL

$($

x

$,$

y

$)$

&Ez

$($

B

$($

x

$,$

y

$,$

z

$)$

&AuB

$($

w

$,$

z

$,$

u

$)$

$)$

Select ALL the variables below if there is any free occurrence of it in the wff

$.$

Group of answer choices

w

y

x

u

z