What caused spain's and portugal's demands for african slaves to grow?

The Spanish and Portuguese were in need of colonial labor force so they had to increase the source for African slaves.

Explanation:

Demand for African slaves was high and the slave trade was controlled by the Portuguese, who set up trading posts on the west coast of Africa. Spanish colonists purchased them directly from Portuguese traders, who in turn purchased them from African traders on the Atlantic coast.

As a result, it was Spain, rather than Portugal, that first made extensive use of enslaved Africans as a colonial labor force.

the fact that could also be added to column b is that during world war ii, specifically between the years 1941 and 1945, japan expanded its territory towards the indonesian territory in what was known later as part of the "pacific war". in that time, japan could conquer the philipines, singapore,   borneo, central java, malang, cebu, sumatra and various other islands of the area, therefore expanding its territory for a brief period of time.