Final answer:
Professor Buchanan delivered a proposal, recommending a specific intercom system after evaluating various options.
Step-by-step explanation:
Professor Buchanan's presentation falls under the category of a proposal. This type of presentation is given to suggest a specific course of action or solution, in this case, the purchase of a particular intercom system. In her presentation, she would have provided information about the different intercom systems available, evaluated them, and concluded with a recommendation for the best option. This aligns with the typical structure of a proposal which includes problem identification, analysis of potential solutions, and the presentation of a recommended solution.