All the triangles are similar, so you know the long side is twice the length of the short side.
x = 2·16 = 32
From the Pythagorean theorem,
z = √(8² + 16²) = √320 = 8√5
Then
y = 2z = 16√5
The appropriate choice is the 2nd choice,
x = 32, y = 16√5, z = 8√5