Final answer:
The Colombian Exchange was started by Christopher Columbus in 1492 and the Maya, Aztec, and Inca civilizations were present before Europeans with their own unique languages.
Step-by-step explanation:
The subject of this question is Social Studies and the grade level is Middle School.
The Colombian Exchange, which started in 1492, was initiated by Christopher Columbus (option b).
Before Europeans arrived, the Maya, Aztec, and Inca civilizations (option d) were present in the Americas. These civilizations had their own unique languages.
Learn more about Colombian Exchange and civilizations in the Americas