Final answer:
Pan-Africanism is the movement aimed at uniting African countries and contributing to the improvement of their economies and political autonomy, influencing Nigeria's independence movement. The correct option is A.
Step-by-step explanation:
The movement whose goal was to unify African countries and help them work together to improve each other's economies, contributing to Nigeria's independence movement, is known as Pan-Africanism. Emerging in the early twentieth century, the Pan-African movement was driven by the desire for African peoples to achieve greater independence.
Influential leaders like W. E. B. Du Bois, Marcus Garvey, and Cheikh Anta Diop played critical roles in advancing the Pan-African movement, and over time, this collective mindset and cultural unity fed into the nationalist movements that sought to end colonial rule and establish self-determination throughout Africa.