In 1994, the united nations sponsored a conference in cairo to discuss
deforestation
global warming
overpopulation issues
the cold war

The correct answer is - overpopulation issues.

The United Nations conference in Cairo in 1994 was on the theme of the Population and Development. The main topic of it was the overpopulation in certain parts of the world and how that could and should be managed so that the world doesn't come in a situation where there will be too many people and don't have sufficient resources for all of them. It was discussed as to how the governments can implement measures to stop or at least decrease this process.

c. the dred scott v. sandford case,

they died because of a disease during the first spanish colonies.