Focus on specific examples of methods you can use/have used to earn backlinks. If you have limited experience earning backlinks, you should spend time reading about the topic before the interview so you can answer the question with confidence.

"Backlinks are created when another website includes a link to your website on their page(s). Essentially, this tells Google that other sources find your content helpful and reliable, which means your site will rank higher. There are a few different factors that determine the quality of backlinks, including the anchor text used, link location, and the authority of the linking domain."