The following sentences should form a coherent paragraph. Select the option which has the odd sentence that does not belong to the thematic unity of the paragraph.

Question and options

1. With the assistance of artificial intelligence (AI) and algorithms, users' search activity on a commercial or search site is directed to brands on social media pages.
2. This technique allows companies to reach their target audience across multiple different platforms.
3. Businesses use a variety of social media platforms with broad audiences for brand promotion, marketing campaigns, and customer engagement.
4. Brand promotion is only limited to one platform.