Why I'm not able to select a subdivision surface along the Y-axis Or Z-axis, Separately?

[bijutoha]

Unfortunately, the selection applies evenly across all Z axes subdivisions; why?

Any insights or advice from the community would be greatly appreciated!

[masterzone]

Se selection tool select polygons under the mouse as a simple brush do. You can’t select preferred polygons but all of them.
If you need into the attributes manager you can turn on “visibile only” for select the first top polygons instead of all in z axis.

[bijutoha]

Thank you so much for your help. However, I solved the problem by removing the N-gongs from their checkbox.