What is the relationship between 'brewing' and 'beer' in the context of the input sentence.
Options: business division, legal form, operator, product/material produced

Founder Christian Ettinger was a business student at the University of Oregon when he first began brewing beer in the early 1990s and remembers when craft or specialty beer consisted of the Killian’s Irish Red, Coors Winterfest and Henry Weinhard’s Dark, Red or Ale.
product/material produced