Who might write a letter to their representatives about a policy issue?
ndividual citizens and the media
individual citizens and political parties
interest groups and the media
interest groups and individual citizens

The correct answer is - interest groups and individual citizens.

Explanation:

If interest groups or individual citizens find an issue with a public policy, they can use a mechanism of addressing their electing representatives by writing a letter or via other form (like submitting quire in representatives's website).

For example, in the European Union individual citizens can address each member of European parliament regarding a public policy introduced by Committee he or she is a member of (e.g. Committee on Civil Liberties, Justice and Home Affairs). Interest groups, such as large influential non-profit organisations, can address elected representatives in a similar way.