The fact that gravity exists as it can be repeatedly tested and verified
Explanation:
A stem cell is a cell with the unique ability to develop into specialised cell types in the body. In the future they may be used to replace cells and tissues that have been damaged or lost due to disease.
I think the answer is Global Development Engineering.
People in this career help sustainable development happen through the use of their inventions that are mainly energy efficienct.
They are focused on research, design, and the creation of alternative ways to promote good health and sanitation, housing, and renewable energy that will cater developing or underdeveloped countries.
GLE is one engineering team that made a solar project in Africa.