Which form of advertising is primarily audio-based?

Podcast ads are primarily audio-based because they are designed to be integrated into audio content, allowing advertisers to reach listeners in a format that aligns with their consumption of podcasts. This type of advertising relies on sound to convey messages, often utilizing the spoken word to engage and inform listeners. Given that podcasts are typically consumed through auditory channels, the effectiveness of this medium lies in its ability to connect with an audience where traditional visual elements would not apply.

The other choices represent formats that incorporate visual elements along with audio or are entirely visual. Video ads, for instance, combine both video and audio elements, while social media ads often prioritize visual content and graphics to capture user attention. Web banners are strictly visual and do not contain any audio components. Consequently, podcast ads stand out as the only option that is fundamentally designed around an audio experience, reinforcing their classification as primarily audio-based advertising.