下列选项中，哪一个是通过夹具将形状ps和物体body连接在一起： A: FixtureDef fd = new FixtureDef(); fd.shape = ps; body.createFixture(fd); B: FixtureDef fd = new FixtureDef(); fd.shape = ps;BodyDef bd=new BodyDef(); body=box2d.createBody(bd); C: Fixture fd = new Fixture(); fd.shape = ps; body.createFixture(fd); D: Fixture fd = new Fixture(); fd.shape = ps;BodyDef bd=new BodyDef(); body=box2d.createBody(bd);