Answer:
a--because of facial characteristics found on large stone heads
Explanation:
Even though the exact origin of the Olmec civilization still remains controversial, anthropologists point out to striking resemblance of the facial features found on huge monolithic heads to Africans.
Moreover, such theory is supported by the argument that some cultural traits found in Olmec civilization closely resemble characteristics of the Egypto-Nubian world of the same time period.
However, despite various theories speculating on the African, Chinese or even Nordic origins of the Olmec, there is no general scientific consensus regarding the issue due to the lack of sufficient evidence that would support such theories
