The statement that best explains why people in West Africa eat manioc is:
"Europeans introduced manioc to Africa after encountering it in America."
This is consistent with the Columbian Exchange, during which various crops, including manioc (also known as cassava), were transferred from the Americas to different parts of the world, including Africa, after European exploration and colonization. Manioc became a staple food in many regions of Africa due to its adaptability to various climates and its nutritional value.