d. Sending money for foreign investments.
Explanation:
The sub-Saharan African countries, in general, tend to be the least developed countries in the world. They have widespread poverty, corruption, terrible politicians (often dictators), lack industry, lack infrastructure, and do not make great use of their vast resources. This of course can change, as the majority of these countries have huge potential for multiple changes will need to be done for it.
Something that will not help the progress of these countries during the 21st century is sending money for foreign investments. Every single possibility needs to be used so that the countries start to develop and strengthen internally, and that would be extremely hard and slow. Sending money abroad for investments will not be a good method because those money will be more than needed in the country itself, for developing infrastructure and industry.
