[megri]

You have moved your site to a new domain name. For users and search engines, the preferred way to permanently redirect traffic is:

Correct answer: a) 301 redirect

Explanation: A 301 redirect is preferred because it tells search engines, "Ok, this is the new domain I want you to show to users from now on," as opposed to something like a 302 redirect, which tells search engines, "Hey, this is only a temporary redirect--so, uh, I might change the URL soon, okay?" In addition to implementing a 301 redirect, the Change of Address feature in Webmaster Tools can help Google find your new site.