Both. Safety requires Red to make a substantial course change to avoid Green that ranks as obstruction. Therefore Red is entitled by rule 20.1 to hail for room to tack. Blue has to respond as required by rule 20.2(c). Because Blue fails to respond she shall be penalized for breaking rule 20.2(c). When it became clear that Blue was not giving room by tacking Red has the possibility to keep clear by passing astern of Green. In failing to do this, she shall be penalized for breaking rule 10.