Answered

How do we know the Olmecs were technically advanced?

AThey created the first version of a calendar
BThey invented tools using stones and metal
CThey used latex from trees to create rubber
DThey were the first to use a writing system

Verified Answer :

DragonPharoah

I believe the answer is B. B. They invented tools using stones and metal 

Amanderfoz

Answer:

C. They used latex from trees to create rubber.

Explanation:

I just took the test