Final answer:
The milestone for the Web site development phase of building an e-commerce presence is a Functional Web site.
Step-by-step explanation:
The milestone for the Web site development phase of building an e-commerce presence is a Functional Web site. This means that the website is fully developed and operational, ready for customers to use for making purchases. A functional website will have features such as product listings, shopping carts, payment gateways, and customer support options.
Other options mentioned in the question, such as a Social media plan, Web mission statement, Web site plan, and Web presence map, are important components of the overall e-commerce strategy, but they are not specifically milestones for the Web site development phase.
For example, a Social media plan is focused on utilizing social media platforms to promote the e-commerce presence, while a Web mission statement is a declaration of the purpose and goals of the website. Both are important, but they are not specific milestones for website development.