Final answer:
Diedre is filling the public relations role by working with environmental groups to promote recycling of food packaging within her organization.
Step-by-step explanation:
The role that Diedre is filling is the public relations role. Public relations is the practice of managing and maintaining a positive image and reputation for an organization or individual. It involves cultivating relationships with various stakeholders, including the media, customers, and community groups.
In this case, Diedre's responsibility of working with environmental groups to promote the recycling of food packaging falls under the purview of public relations. She is actively engaging with external stakeholders to create a positive impact and build good relations.