Refer to the input text as context and select the correct relationship between 'Stratasys' and '3D printing' from the available options.
Options: product/material produced, member of, distributed by, distribution format

Troy Jensen at Piper Jaffray said that the 3D printing industry is "starting to show signs of reacceleration," with the outlook for Stratasys being more positive than that for 3D Systems.
product/material produced