D. Mansa Musa’s pilgrimage
While Mansa Musa's pilgrimage did bring attention to the wealth of the Mali Empire, it was not a direct contributor to the ongoing wealth of the empire itself in terms of trade or resources. The other options (A, B, and C) directly relate to the economic activities that contributed to the wealth of the Mali Empire. Mansa Musa's lavish spending during the pilgrimage may have even impacted the value of gold negatively in the long run.