Which of the following terms is used for the second leg of the route known as the triangular trade, which carried enslaved Africans to the Americans?

Though we don't have the options it's possible to answer this question directly: the correct term is middle passage.

First leg: The triangular trade connected America, Europe, and Africa. From Europe to Africa traveled textiles, rum and manufactured goods that were used to buy slaves.

Second leg: recently bought slaves traveled from Africa to America. This travel is what we call the middle passage.

Third leg: sugar and cotton produced in America by slave labor are taken and sold in Europe.