Multiple choice

In order for life as we know it to exist, a planet must have ______________________

  1. an axis.

  2. ice.

  3. liquid water.

  4. salt.

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Liquid water is considered essential for life as we know it because it acts as a universal solvent for biochemical reactions. While ice, salt, and axes exist on various planets, none are as fundamental to life-sustaining processes as liquid water.