I believe the answer is: the hospital
Conditioned stimulus refers to a stimulus that already become a trigger to a certain response due to the process of classical conditioning. From the example above, alexis start to cry after she saw a hospital. Because of this, we can say that the sight of hospital act as the trigger the elicit the response.
But responsibility for the slave trade is not simple. On the one hand, it was indeed the Europeans who purchased large numbers of Africans, and sent them far away to work in their colonies. On the other hand, Africans bear some responsibility themselves: some African societies had long had their own slaves, and they cooperated with the Europeans to sell other Africans into slavery. The Europeans relied on African merchants, soldiers and rulers to get slaves for them, which they then bought, at convenient seaports.
Africans were not strangers to the slave trade, or to the keeping of slaves. There had been considerable trading of Africans as slaves by Islamic Arab merchants in North Africa since the year 900. When Leo Africanus travelled to West Africa in the 1500s, he recorded in his The Description of Africa and of the Notable Things Therein Contained that, "slaves are the next highest commodity in the marketplace. There is a place where they sell countless slaves on market days." Criminals and prisoners of war, as well as political prisoners were often sold in the marketplaces in Gao, Jenne and Timbuktu.
Perhaps because slavery and slave trading had long existed in much of Africa (though perhaps in forms less brutal than the slavery practised in the Americas), Africans were untroubled by selling slaves to Europeans.
The important things you should examine are the presidents formal and informal powers.Formal power includes the presidents are the appointment of ambassadors and making and signing treaties with other countries. In informal the president can initiate and enact a legislative agenda, he can send out troops without declaring war.
