Final answer:
Charlie Christian's career received a significant boost from record producer John Hammond, who played a pivotal role in the advancement of many American musicians, contributing to the cultural and historical developments in music.
Step-by-step explanation:
The record producer who gave a boost to Charlie Christian's career was John Hammond. Hammond was known for his role in discovering and promoting several musicians who would become monumental figures in American music. Charlie Christian, an influential jazz guitarist, was one of the beneficiaries of Hammond's support. This collaboration is a part of a larger history of how African American musicians, including Chuck Berry and Elvis Presley, contributed to the development of rock 'n' roll. Their music reflected a blend of diverse musical influences and in the process helped break down racial barriers and appeal to a wide audience.