Which of the following best exemplifies a multi-platform campaign?

Creating a YouTube series sharing the ‘making of’ and ‘behind the scenes’ of the campaign launch.

Sending out weekly newsletters to summarise all campaign aspects of the week to catch the audience up on any posts they may have missed.

Using an app to ensure that one post is shared among many chosen platforms.

Launching a product with a series of blog posts, social media teasers, and a promotional video.

Using an app to ensure that one post is shared among many chosen platforms.