Question

fff: holes
use the information below to answer the question.
vertical holes
a hole displayed on a computer will be slightly narrower when printed in a part. the
size will be determined by three things:

1. material
2. slicer setting
3. the printer

a user may need to run test builds to see exactly how the hole will be formed. the
printed hole is narrower than how it looks in the design file because each layer of
molten polymer presses down on the layer beneath it, causing the material to be
squeezed into the inside circumference of the hole.
horizontal holes
horizontal holes are not ideal, as they will have bridging. this is especially true with
the formation of smaller holes. the hole will tend to be an oval shape, and it can be
challenging to remove all of the support material.
a good strategy for printing holes in a design is to rotate the part, changing horizontal
holes into vertical holes. the user would then need to compensate for the effect that
the printing process has on the holes.
why is the printed hole narrower than how it looks in the
design file?
because prints are double their actual size when shown in a design file
because design software can only display holes at a set size for all prints
because every print will often run out of material at the end of the process
because each layer of molten polymer presses down on the layer beneath it

Explanation:

The text explicitly states that the printed hole is narrower than the design file because each layer of molten polymer presses down on the layer beneath it, squeezing material into the hole's inner circumference. This directly matches one of the options.

Answer:

because each layer of molten polymer presses down on the layer beneath it