Which statement about lightning is true

Which statement about lightning is true?
a.
It is one of the most dangerous parts of a thunderstorm.
b.
It is an electric discharge between two similarly charged surfaces.
c.
It is caused by the rapid expansion of air along an electrical strike.
d.
It always begins in a cloud and strikes the Earth.

A - It is one of the most dangerous parts of a thunderstorm.

Lightning is one of the top dangers of a thunderstorm. Many people remain outdoors during a thunderstorm and lightning occurs without much of a warning, thus people are caught offguard.