Caeleb Dressel, the fast swimmer in the world and a recent olympic champion in the 100 meter free style is paid by Speedo to mention Speedo's line of high performance swimming gear on social media & faceook. Caeleb also wears Speedo apparel at competitons. this is an example of Speedo using ------ to promote its product.

1. Personal Selling
2. Advertising
3. Sales promotion
4. publicity
5. none of the above are correct