Which of these choices best represents the continents involved in the system of "triangular trade"? a) 1, 2, & 4 b) 1, 3, & 4 c) 3, 4, & 5 d) 4, 5, & 6

Because you have not provided the continents list, let me simply explain the triangle trade and who it involved.

the triangle trade was an intercontinental trade that took place across the transatlantic and Mediterranean sea.

The key items of trade were slaves, finished products such as textile and sugar, and their raw materials.
 The continents involved were Africa,Europe and america
Africa was the source of slaves, America was the source of raw materials and Europe the source of finished products..

The correct answer is 1, 3, & 4, because they represent North America, Africa, and Europe, respectively. (These continents are often placed in a historical context as "The Atlantic World.") The system, which existed during the era of mercantilism, saw slaves sent from Africa to the Americas, raw goods sent to Europe, and manufactured goods- such as guns and liquor- sent to Africa. Historians often include South America in the system, but that is not a choice here.