Question on GMAT Prep Math:

If XY+Z = X(Y+Z), which of the following is true:
a). x=0, z=0
b). x=1, y=1
c). y=1, z=0
d). x=1, y=0
e). x=1, z=0

The answer is E.

I'm not sure why (E) is true since it shows: Y = Y
But (A) gives you 0=0 which is also true
and (D) shows Z = Z

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