Which of the following is not an example of a pull factor that encourages voluntary migration

Slave ship or slave ship were the denominations of the ships dedicated to the black slave trade, especially those of the Atlantic slave trade between Africa and America, as part of the triangular trade, called in English middle passage. Some twenty million African slaves were transported by these boats.

The Atlantic slave trade became a big business with the colonization of America, which demanded slave labor for the plantations. The seventeenth and eighteenth centuries marked the highest level of this traffic.

In most cases the captains of these ships received conceptions of the lands of the new colonies.