When was the style of american blues developed?

a. colonial america
b. during the great depression
c. during the vietnam war
d. the early 20th century

The style of American blues was developed in the early 20th century. Correct D Blues is a music genre created by African Americans in the early 20th century, originally in the South. The name blues comes for "the blue devils,” which denoted intense visual hallucinations that can accompany severe alcohol withdrawal. Over time it was shortened to  “the blues,”.

the answer is a i had that before

81 is a composite number.