Which of these characteristics of Earth is NOT essential for supporting life as we know it? a) Presence of liquid water b) Suitable distance from the Sun c) Presence of a magnetic field d) Composition of the atmosphere

What force is primarily responsible for governing the motion of planets around the Sun? a) Magnetism b) Gravity c) Friction d) Electrostatic force

Which of these is NOT a way that humans depend on ocean systems? a) Food source b) Climate regulation c) Transportation d) Source of fossil fuels