According to historian arnold toynbee, ibn khaldun developed “philosophy of history”. why was this a significant achievement?

Arnold J. Toynbee (1889 – 1975) was a British and philosopher remembered for his great “Study of History” which is a big work of 12 volumes that analyze 21 civilizations; their rises and falls.

His work is a combination of philosophical and objective thoughts, so this insures the combination of facts that are analyzed from two perspectives, because he is using concrete historical events combined with his philosophical and empirical ideas. That is why  many historians, philosophers, sociologists, political scientists are interested in his books and how civilizations emerged, grew, declined and dissolve themselves.

i would say b. or c.