The choices can be found elsewhere and as follows:
a.
copper alloy or bronze casting were first used in Sub Saharan Africa.
b.
Islam became an economic and religious force in West and North Africa.
c.
that abstract thought in humans occurred much earlier than once thought.
d.
the French colonies were taken over before the third or fourth centuries.
I think the correct answer is option C. The discovery of the Blombos cave suggests that abstract thought in humans occurred much earlier than once thought.
