Question

which keywords would be most effective to find research on the development of a cure for slowing down or decelerating human aging?
aging
old and research
aging and development and people
aging and research and cure

Explanation:

The goal is to find research on a cure for slowing human aging. The keyword set "aging AND research AND cure" includes all essential elements - the subject of aging, the activity of research, and the desired outcome of a cure. The other options lack either the focus on research or the mention of a cure.

Answer:

aging AND research AND cure