Question

the discovery of the blombos cave suggests
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.

Explanation:

The Blombos Cave discoveries (like engraved ochre and shell beads) show evidence of early abstract thought (symbolic behavior, planning, etc.) in humans, pushing back the timeline of such cognitive abilities. Option a is about metalworking (not Blombos' focus), b about Islam (too late chronologically), d about French colonies (irrelevant to Blombos Cave's paleolithic/early human context).

Answer:

c. that abstract thought in humans occurred much earlier than once thought.