✪ Choose the correct option.
A valuable sword belonging to the Grand King was stolen, and the three suspects were Ibn, Hasan and Abu. Ibn claimed that Hasan stole it, and Hasan claimed that Abu stole it. It was not clear that one of them stole it, but it was later learnt that no innocent person had lied. It was also learnt that the sword was stolen by only one person.
Who stole the sword?