Human: What is the name of the opening where White plays 2. c4? Assistant: 
The most important closed openings are in the Queen's Gambit family (White plays 2. c4). The Queen's Gambit is somewhat misnamed, since White can always regain the offered pawn if desired. In the Queen's Gambit Accepted, Black plays... dxc4, giving up the center for free development and the chance to try to give White an isolated queen pawn with a subsequent... c5 and... cxd4.