To determine which statement proves that the dilation of triangle \( \Delta XYZ \) does not pass through the center of dilation, we need to identify the option that explains how the lines corresponding to the segments of the triangles are not originating from the center of dilation.
The statement that best supports this is:
XY has a length of 3 and X′Y′ has a length of 1, which proves that ΔX′Y′Z′ is a dilation of ΔXYZ by a scale factor of 1/3.
However, this particular response does not directly suggest that the dilation does not pass through the center of dilation, so let's look at the other statement:
XY and X′Y′ both have an undefined slope with a center of dilation at (0,0). This proves that the lines are parallel and that the dilation does not pass through the center of dilation.
This option clearly demonstrates that since the lines are parallel (having the same undefined slope), they do not converge at the center of dilation, which is set at (0,0). Thus, this statement accurately proves that the dilation of \( \Delta XYZ \) does not pass through the center of dilation.
Therefore, the correct answer is the statement regarding their slopes being undefined, making them parallel and confirming that the dilation does not pass through the center.