Because they can craft objects of a new design without having extrusion fittings custom-designed for that purpose, 3D printers have an application in building prototypes of new models of objects long before those new models are on production lines, and it was on this basis that they first captured the interest of the market. However, suitability for prototyping does not limit 3D printers to prototyping, and in fact their capability to craft items without specialized fittings for each design can allow them, in essence, to be the production line. 3D printers have this natural application to mass-production in part because they can produce items at a cost competitive with that of production lines.
In the argument given, the two portions in boldface play which of the following roles?
【选项】
The first and the second each describe evidence that has been used to challenge the position that the argument seeks to establish.
选项是否正确？