What model of foreign policy decision-making involves a struggle among government agencies with differing interests?

The model of foreign policy decision-making that involves a struggle among government agencies with differing interests is bureaucratic politics. This approach emphasizes that decisions are the result of negotiation and competition among various governmental actors, each with their own agendas and priorities.

In bureaucratic politics, the dynamics of power and influence among different agencies play a significant role in shaping foreign policy outcomes. The decisions are not merely a product of a single leader's preferences but are the result of conflicting interests and negotiations among various departments, each advocating for their perspective based on their unique missions, resources, and viewpoints. This model highlights how internal government processes and inter-agency rivalries can significantly affect international relations.

Collective decision-making differs in that it implies a more unified approach where various entities work together towards a common goal without significant power struggles. Individual decision-making highlights the role of a single actor or leader in the process, which doesn’t encapsulate the agency-level conflicts present in bureaucratic politics. Elite decision-making focuses on a small group of influential individuals, ignoring the broader and more complex interactions between various governmental agencies. Each of these alternatives lacks the emphasis on the inter-agency competition that characterizes bureaucratic politics, making it the most fitting answer to the question posed.