Final answer:
Mark's choice of a top-level domain does not directly impact the mobile optimization of a website, which is more about design and development. However, selecting a memorable and content-appropriate TLD, such as '.com', '.net', '.org', or '.app', is beneficial for brand recognition.
Step-by-step explanation:
If Mark is developing a website optimized for mobile devices, the choice of a top-level domain (TLD) doesn't directly affect the mobile optimization of the website. Optimization for mobile devices typically involves responsive design, fast loading speeds, and user-friendly navigation, which are related to the website's design and development rather than its domain name. However, choosing a TLD that is memorable and appropriate for the website's content is important for brand recognition and user trust. Popular choices include '.com', '.net', and '.org', while specialized TLDs like '.app' can also be relevant, especially if the website has an associated mobile application.