Which of the following statements about FDM printing is true?

Fused Deposition Modeling (FDM) printing is a widely-used additive manufacturing process that indeed relies on an extruder to deposit thermoplastic material. In FDM, the printer melts a filament made of thermoplastic, which is then precisely extruded through a heated nozzle layer by layer to build up the desired part. This method allows for effective layer-by-layer construction, providing control over material deposition and creating complex geometries.

The other statements do not accurately describe FDM printing. For instance, laser sintering refers to a different manufacturing process known as Selective Laser Sintering (SLS), which uses a laser to fuse powdered material rather than extruding thermoplastics. FDM does not require a vacuum chamber; it operates in ambient conditions. Lastly, while FDM can create fine details, it typically produces parts with visible layers due to the nature of the layer-by-layer construction process. Thus, the characterization of FDM relies directly on the function of the extruder to deposit material, which solidifies the accuracy of the chosen answer.