The answer is D: placed more emphasis on music as part of church services.
Explanation for each option:
A. Held more performances of blues music - This option is incorrect because African-American churches were not primarily known for performances of blues music. While blues music has roots in African-American culture, it was not typically performed in church services, which focused more on gospel and spiritual music.
B. Were the sole influence on the development of blues music - This option is incorrect because the development of blues music was influenced by a variety of factors, including African musical traditions, work songs, and field hollers, not solely by African-American churches.
C. Had fewer financial assets - This option is incorrect because the passage does not provide information about the financial assets of African-American churches compared to other churches.
D. Placed more emphasis on music as part of church services - This option is correct because African-American churches are historically known for their vibrant and integral use of music in worship, often incorporating gospel music, which is a significant aspect of their services.