Which of the following statements is true about Earth's atmosphere?

A) It formed from gases released from rocks in early Earth.
B) Its composition has changed over the history of Earth.
C) It originally had much more oxygen than today, making the early atmosphere toxic to most of the life that exists today.
D) a and b
E) a, b, and c

Earth's Atmosphere

The layer of gases surrounding Earth, vital for life, retaining heat, and protecting organisms from ultraviolet solar radiation.

Gases

States of matter consisting of particles that have neither a defined volume nor shape, expanding freely to fill the container they are in.

Composition

The way in which various components or elements are arranged and combined to form a whole, applicable in art, literature, and science.