Final answer:
The crucifixion plaque from the Kingdom of Kongo is most accurately titled an ivory sculpture, serving both as a religious and historical artifact reflecting a blend of Kongo and Christian traditions.
Step-by-step explanation:
The title of the crucifixion plaque from the Kingdom of Kongo is best described as an ivory sculpture. This piece is a seventeenth century artifact made by Portuguese missionaries who combined Kongo customs with Christian iconography, specifically representing Christ as an African. It serves as a religious artifact due to its sacred content and use within Christian practices. Moreover, it reflects the culture and religious perspectives of the Kingdom of Kongo during that period, also making it a significant historical artifact. The plaque represents a unique blend of Kongo authority symbols, such as scepters and staffs, signifying power with the Christian image of the crucifixion of Jesus.