What is the relationship between 3D Systems and 3D printing in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

The 3D printing pioneers Stratasys Ltd. ( SSYS ) and 3D Systems Corp. ( DDD ) touched highs of $120.36 and $80.13 in 2014 and 2013 respectively.

Answer: industry