Final answer:
George Pullen Jackson is recognized as the father of modern black gospel music due to his documentation and research on lined-out hymns and their influence on gospel music.
Step-by-step explanation:
The father of modern black gospel music is George Pullen Jackson. He was a folklorist and professor who visited black Primitive Baptist churches in Alabama and Jacksonville, Florida in the 1940s. He heard congregants still singing lined-out hymns, which he sometimes called "surge songs," with great power and beauty. Jackson's documentation and research on these hymns and their influence on gospel music helped establish him as a significant figure in the development of modern black gospel music.