The correct answer is - B. The Mongolian conquest of Persia ended a golden age, which was a peak period of Islamic literature, philosophy, medicine, and art.
The Mongols conquered Persia and destroyed lot of cities, killed lot of people, and put end to the Islamic Caliphates, though it has to be said that the Mongols were actually provoked, and initially were not the ones that were seeking war.
By conquering the region, the Mongols put an end to the so called Islamic Golden Age, when the Islamic literature, philosophy, art, medicine, culture as a whole, was at its peak. Unfortunately, even after the Mongols left, the Muslim countries never got back to their glorious and forward thinking ways, and the reason for that is that some of the most influential Islamic scholars declared the math as a work of the devil, which pretty much cut all further development in the Middle Ages, and still has big negative effects in the present.
