Definition: In this task, you're given a question, along with a context passage. The passage will not have a direct answer to the question, but can include some information and a clue for the answer. Assuming you can only obtain information about one entity in the passage, your job is to determine whether information from the passage can be used to answer the question. Indicate your choice as `a` for Yes or `b` for No.
Input: Question: What time period did the Antonine dynasty rule? Passage:Commodus, the last emperor of the Antonine dynasty, remembered by contemporaneous chronicles as an unpopular ruler notorious for his extravagance and cruelty, was assassinated in 192. Without sons to be his heir, a struggle for power immediately broke out amongst the governors of the most important provinces. Pertinax was elevated to the purple and recognized by his peers, but following his murder by a restive Praetorian Guard, Septimius Severus decided to make his bid for power and usurped the throne. Although initially a usurper, Severus managed to remain in power for the next 18 years and died a natural death while campaigning in northern Britain. The death of Severus Alexander (the last emperor of the Severan dynasty) in 235 triggered what historians call the crisis of the third century. In this period, from 235 to the accession of Diocletian and the establishment of the Tetrarchy in 286, Rome saw 28 emperors of whom only two had a natural death (from the plague). However, there were also 38 usurpers who raised revolts across the Empire, a clear sign that the security of the frontiers was not the only problem within the Roman world. Usurpation attempts were a constant worry for the emperors in this period; it was a too common method of acceding the throne. Successful usurpers were usually either provincial governors, commanders of a large grouping of Roman legions, or prefects of the Praetorian Guard, which had control of Rome, where the Imperial palace still lay.


b