You are presented with the quiz "A scientist who is a space explorer requires what for extended flights?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "astronauts require preserved food for extended flights" and "an astronaut is a scientist who is a space explorer". So, what's the best answer to the question?

Options:
[1]. preserved food;
[2]. salt and water.;
[3]. hydration;
[4]. a hydraulic system;
[5]. useless heavy objects;
[6]. short-lived food;
[7]. hydrate their cells;
[8]. perishable food;
Answer:
[1].