The theory that argues that media can have a strong influence in deciding the small number of public problems or issues that people will think about at any given point in time, is:

The theory that media strongly shape the small set of public issues people think about at a given time is agenda-setting.

Media do this by giving prominence to some issues while playing down others.

The knowledge-gap theory instead concerns how information tends to reach better-off groups faster.

The limited effects theory argues that media influence is usually weak and mediated by other factors.

The personal influence theory stresses the role of interpersonal contacts and opinion leaders.

Agenda-setting was set out by Maxwell McCombs and Donald Shaw from their 1968 Chapel Hill study.