B. Byzantine culture; and
D. Orthodox Christianity
In the Middle Ages, the Kingdom of Serbia was an independent kingdom under the Vlastimirović dynasty. But after that dynasty faded in the 10th century, Serbian territory fell under Bulgarian or Hungarian or Byzantine control. The Byzantine influence was long-lasting. So also was the influence of Orthodox Christianity, which had been adopted as the state religion of Serbia in the 9th century. By the 13th century, the Serbian Orthodox Church was recognized as an independent partner church within the Eastern Orthodox communion.