Which of the following is true?
A. Lightning is relatively uncommon on Earth.
B. Thunder is caused by rapid contraction of the air.
C. Thunder is caused by rapid cooling of the air.
D. Lightning results from the build up of electrical-energy polarity within clouds.

the correct answer is D. LIGHTNING results from the build up of electrical-energy polarity within clouds.

Explanation:

In simple words, Lightning is defined as a flash of light that is caused by the discharge of electricity in the atmosphere. An example of lightning is the flash of light often seen before the thunder is heard

Lightning is a naturally occurring electrostatic discharge during which two electrically charged regions in the atmosphere or ground temporarily equalize themselves, causing the instantaneous release of as much as one gigajoule of energy.

Lightning can be either connect from one cloud to another, or shoot from a cloud down to the ground. Lighting also has different appearances and is always accompanied by thunder. Types of cloud-to-ground lightning include staccato, forked, ribbon, and bead lightening.