What Is the Scientific Consensus from Studying the Evidence of Iron-Working

What is the scientific consensus from studying the evidence of iron-working in Africa?

A) It appears to have occurred at different times in northern and southern Africa.
B) Iron-working in both areas appears to indicate that northern and southern Africa developed independently of each other.
C) Iron-working techniques of both northern and southern Africa are very similar.
D) Metal-working appeared in Egypt before anywhere else in Africa.
E) Metal-working began in Sudan and moved north along trade routes.