What is the relationship between 'Stratasys' and '3D printing' in the context of the input sentence.
Options: legal form, developer, location of formation, product/material produced

MakerBot's performance Over the last two quarters, MakerBot's performance has become a sensitive subject for Stratasys because the consumer 3D printing unit's revenue growth rate has fallen off a cliff since the third quarter of last year: Source: Stratasys
product/material produced