In an experiment, each volunteer was allowed to choose between an easy task and a hard task and was told that another volunteer would do the other task. Each volunteer could also choose to have a computer assign the two tasks randomly. Most volunteers chose the easy task for themselves and under questioning later said they had acted fairly. But when the scenario was described to another group of volunteers, almost all said choosing the easy task would be unfair. This shows that most people apply weaker moral standards to themselves than to others. Which of the following is an assumption required by this argument? ['The most moral choice for the volunteers would have been to have the computer assign the two tasks randomly.', 'At least some volunteers given the choice between assigning the tasks themselves and having the computer assign them felt that they had made the only fair choice available to them.', 'On average, the volunteers to whom the scenario was described were more accurate in their moral judgments than the other volunteers were.', 'At least some volunteers who said they had acted fairly in choosing the easy task would have said that it was unfair for someone else to do so.']