Final answer:
b) Infrastructure is not considered a primary motive for new imperialism; main motives included economic desire, Social Darwinism, and the White Man's Burden.
Step-by-step explanation:
The concept not considered a primary motivation for the emergence of new imperialism among the provided options is b) Infrastructure. The primary motivations for new imperialism in the 19th century included economic desire, such as gaining access to raw materials, a belief in Social Darwinism, which suggested that European nations were naturally superior and destined to rule over 'lesser' nations, and the concept of the 'White Man's Burden', which was the idea that Western powers had a duty to bring their 'civilization' to the 'uncivilized' parts of the world.
Infrastructure development was a result of imperialistic activities rather than a driving force behind imperialism's emergence.