About 21% of Earth's atmosphere is composed of oxygen. Oxygen can combine with other substances. The chemical reaction of oxygen with other substances is called oxidation and it is a source of chemical weathering. The building on the left has undergone oxidation; compare it with the picture of the rock on the right. The rock has changed much like the building.

What is the best explanation for how the rock on the right has changed over time?

Responses

Chemical weathering has happened due to acid rain in the area.
Chemical weathering has happened due to acid rain in the area.

Water in the atmosphere has caused the rock to rust; it has physically weathered.
Water in the atmosphere has caused the rock to rust; it has physically weathered.

Oxygen has chemically reacted with the minerals in the rock; oxidation has occurred.
Oxygen has chemically reacted with the minerals in the rock; oxidation has occurred.

Physical weathering has taken place and the rock is broken down into smaller pieces.