Your answer to this question must be guided by the course materials you have been provided. There is a very close connection between nationalism, imperialism, and scientific racism starting in the nineteenth century.
In the 1870s, Europe's second wave of the Industrial Revolution spurred European nations' desire for access to raw materials. As a result, many European nations wanted overseas empires. For example, King Leopold II of Belgium began to enslave the people of the Congo in his pursuit of ivory and, later, rubber. When other nations saw his actions, they were motivated by a sense of nationalism (or the idea that their nation was destined for greatness) to pursue overseas colonies in Africa, Asia, and the Middle East. (The United States was also motivated to be imperialist, mainly in the New World but also in the Pacific.) Many nations such as Germany had just united (in 1871), driving these recent countries to use imperialism to promote their new nations and unite their people.
The philosophy of scientific racism developed in part from Darwin's monumental work, On the Origin of Species (1859), which uncovered the mechanisms of heredity. Other thinkers, such as Francis Galton, who was Darwin's cousin, applied Darwin's ideas to the study of human heredity and determined (falsely) that human ability is entirely heritable. Galton began the study of eugenics, the creation of a "master race" through genetic engineering. The idea of a superior race fueled nationalism and imperialism, as Europeans and Americans believed that they were superior to other people and had a right to conquer others and "civilize them." Therefore, these three ideas were closely interconnected.