Scott Joplin was a very popular and successful Ragtime songwriter in the 1800s. He was known as the "King of Ragtime" and composed 44 Ragtime pieces, as well as two ballets, and a Ragtime ballet. The other three artists were popular musicians in the 1950s and 1960s and did not record in the Ragtime era or style.

This sentence gives no reason to add any commas what so ever. This would be a straight forward run-on sentence that would need no clause, pauses or anything that would break this sentence down any more.
Option B would give clear and straight forward information. The first option broke this sentence down as we can see, and as for this, this would not be the proper way of expressing this sentence. Therefore, your
last option would then be your answer.
They were composed of paternal clans!
i think the answer will be
B:
an oath of loyalty.