Question

fff: anisotropy
use the information below to answer the question.
things created with fused filament fabrication (fff) are inherently stronger in one direction than in another. the term for this anisotropy. things parallel to the print bed (the xy axis) are stronger than those that are perpendicular to it (the z axis). a good example of something that is anisotropic is timber. it is much easier to split wood going with the grain rather than going across it.
with fff, layer adhesion is based on the printer calibration and operating parameters. this is set by the person operating the printer. when designing a functional piece, the user should identify which direction it is being printed to take advantage of the technology. stresses build up in the valleys between each layer as well. layers are weak in the z axis. a user can optimize the print by having two parts. a strong axis nested against a weaker one will support the part.
in terms of fused filament fabrication (fff), in which axis are layers weak?
the z axis
the y axis
the e axis
the x axis

Explanation:

The text clearly states that in Fused Filament Fabrication (FFF), things parallel to the print bed (XY axis) are stronger, and layers are weak in the Z axis.

Answer:

the Z axis