If Square ABCD is dilated by a scale factor of two about the center of the square, dilated line E'F' will?

EF passes through the center point. Let's call the center point G All lines that pass through the center of dilation will still pass through the center after the dilation. So what this means is that segment E'F' will also pass through point G In fact, segment E'F' will lay entirely on line EF