The impact of al-Masur on Islam is best captured by option B: He moved the capital of the Abbasid Dynasty to Baghdad and unified the kingdom.
Al-Masur, a significant figure during the Abbasid Caliphate, played a crucial role in establishing Baghdad as a center of culture, politics, and learning, which greatly influenced the development of Islamic civilization. This move helped to unify the diverse regions of the empire and fostered an environment where intellectual and cultural exchange could flourish. Baghdad became known for its advancements in various fields, including science, philosophy, and the arts, which were integral to the Islamic Golden Age.
While options A, C, and D reflect activities related to the intellectual and cultural achievements of the period, the most direct and substantial impact of al-Masur on Islam is indeed the establishment of Baghdad as the capital, which provided a centralized administration and stimulated the growth of Islamic culture and scholarship.