Final answer:
Mathilde's grocery business practices, including buying items in bulk and promoting customer satisfaction, reflect the norms of the economic social institution.
Step-by-step explanation:
The actions and practices of Mathilde in her grocery business exemplify the norms associated with the economic social institution. In sociology, the economy refers to the institution through which society's resources are exchanged and managed. Mathilde's practice of buying items in bulk and selling them at a higher price illustrates her engagement in economic activities to generate profit, which is a core aspect of economic systems. Furthermore, her approach to customer service, which includes being polite and offering replacements for unsatisfactory goods, promotes repeat business and customer satisfaction, reflecting a strategic understanding of economic principles like utility, consumer choices, and behavioral economics.