From now, Google Webmaster Help To Provide Mobile Optimization Tutorials in three columns like responsive design, dynamic serving & mobile version of website. But remember Google gives preference to Responsive website but it supports all three version.
Here is screenshot below :
Google Webmaster also announced the same message on their official Google+ page :
There are three common configurations of #mobilefriendly sites: Responsive web design, dynamic serving, and separate mobile URLs. Whichever configuration you choose is up to you—Google supports all three. We’ll go into more detail on each of these three methods this week. Here’s a chart of the key differences.