Question

fff: layer adhesion
use the information below to answer the question
layer adhesion occurs during the process of a new layer of plastic being printed on top
of a previous layer.
printing process
when plastic is printed, it comes out hot, but immediately begins cooling.
when the next layer is printed, the heat from the new layer warms up the previous
layer and welds the two layers together, creating a physical bond.
in between each layer of plastic, a valley will form. valleys are created by the print
head pushing down on the previous layer as it is printing the next layer of plastic -
creating a slight dip in the surface between each layer.
when the filament is first printed, it comes out in a circular shape. as the new layer is
fabricated, the pressure from the print head pushes down on the previous layer,
causing it to deform slightly into an oval shape.
where would you find valleys in your print?
wherever the design calls for a portion to be printed lower than the majority
of the part
places where the machine stops working properly and heats up too much
plastic
on the outside surface, in between each layer of the print

Explanation:

According to the text, valleys are formed between each layer of plastic. The first option is about design - called lower portions (not related to layer - by - layer valley formation as described). The second option is about machine malfunction (not relevant to the described valley - formation mechanism). The third option aligns with the description in the text that valleys are between each layer of the print on the outside surface.

Answer:

on the outside surface, in between each layer of the print