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: How long is the river that bordered the land occupied by Bavarians? Passage:In the meantime, the Germanic tribe of the Bavarii (Bavarians), vassals of the Franks, had developed in the 5th and 6th century in the west of the country and in what is now known as Bavaria, while what is today Vorarlberg had been settled by the Alemans. In the northern alps the Bavarians had become established as a stem dukedom around 550 AD, under the rule of the Agilolfings until 788 as an eastern outpost of the Frankish Empire. At that time the lands occupied by the Bavarians extended south to current South Tyrol, and east to the river Enns. The administrative center was at Regensburg. Those groups mixed with the Rhaeto-Romanic population and pushed it up into the mountains along the Puster Valley.


b