Final answer:
Burt is acting as a referral source for Sharon.
Step-by-step explanation:
Based on the information provided, Burt is acting as a referral source for Sharon.
A referral source is someone who recommends a business, product, or service to others. In this case, Burt was happy with Sharon's products and spoke with other manufacturers who are interested in working with her.
Sharon can now contact these manufacturers as potential business partners and explore collaboration opportunities.