What does "inventory" refer to in the context of broadcasting?

In the context of broadcasting, "inventory" primarily refers to the total number of avails, or available advertising slots, throughout a programming schedule. This concept is crucial for broadcasters as it represents the amount of airtime they have available to sell to advertisers. Understanding inventory allows broadcasters to maximize their revenue by effectively managing and selling their advertising space.

While the other options involve important aspects of broadcasting, they do not capture the essence of what "inventory" means. Creative assets for advertisements pertain to the content of the ads themselves, viewer demographic information relates to the target audience characteristics, and daily ratings figures provide insights into audience viewership patterns, none of which directly reflect the concept of available advertising slots or inventory. Thus, the correct answer signifies the specific focus on the opportunities available for advertisers within a broadcast schedule.