How did the Silla turn Korea into an economic and cultural center

Silla was one of the three kingdoms of Korea, with Baekje and Goguryeo, later known as Goryeo. Silla was the earliest-founded of those three kingdoms, and was the smallest and weakest of the three, but later they were able to make pacts and alliances that improved their status. Once Silla was unified and stablished they had a rapid emergence of religion, commerce and art, that turned Silla and Korea into an economic and cultural center.

i would say the answer is

D. by carrying Confucian and Buddhist ideas to Japan

because when you read what she says at the top it sounds the same way as this answer