Astronauts require preserved food for extended flights, and an astronaut is a scientist who is a space explorer. Given these facts, a scientist who is a space explorer requires what for extended flights among the following options:
- preserved food
 - salt and water.
 - hydration
 - a hydraulic system
 - useless heavy objects
 - short-lived food
 - hydrate their cells
 - perishable food


 

 preserved food        