Final answer:
Chess Records was not primarily an R&B label in the 1960s, unlike Motown, Stax, and OKeh which were key R&B labels.
Step-by-step explanation:
The record company that was NOT an R&B label from the 1960s among the options listed is Chess Records. While Chess did release some R&B music, it was more known for its focus on blues and rock and roll. Motown, Stax, and OKeh were all significant players in the R&B scene in the sixties, whereas Chess was primarily associated with artists such as Muddy Waters, Howlin' Wolf, and Chuck Berry, who were blues and rock and roll musicians.