B i.e. Atracurium You might be thinking that this Q has never been asked, but think a while and try to understand that around which concept the Q is based. In other words, they are trying to ask that which muscle relaxant will not require reversal? I think now you need no explanation - In pancuronium reversal is often required d/ t its longer duration of action - Ve/Ro-curonium seldom require reversal unless repeated doses have been given - In atracurium & cis-atracurium reversal is mostly not required due to its unique feature of spontaneous non eyzmatic degradation (Hoffmann elimination) Q.