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 had Ferdinand I been in power the year Coimbra fell? Passage:The history of the county of Portugal is traditionally dated from the reconquest of Portus Cale (Porto) by Vímara Peres in 868. He was named a count and given control of the frontier region between the Limia and Douro rivers by Alfonso III of Asturias. South of the Douro, another border county would be formed decades later when what would become the County of Coimbra was conquered from the Moors by Hermenegildo Guterres. This moved the frontier away from the southern bounds of the county of Portugal, but it was still subject to repeated campaigns from the Caliphate of Córdoba. The recapture of Coimbra by Almanzor in 987 again placed the County of Portugal on the southern frontier of the Leonese state for most of the rest of the first county's existence. The regions to its south were only again conquered in the reign of Ferdinand I of León and Castile, with Lamego falling in 1057, Viseu in 1058 and finally Coimbra in 1064.


b