The university, particularly the University of Sankore, was the main feature that made Timbuktu a center of intellectual advances and culture. It attracted scholars and facilitated the exchange of ideas. Therefore, the correct answer is D. the university.
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Timbuktu was a significant center of intellectual advances due to its university, particularly the University of Sankore, which attracted scholars globally. The city's libraries and mosques also played a vital role in nurturing knowledge and culture during its peak. Overall, Timbuktu's educational institutions facilitated the exchange of diverse ideas and learning. ;