Question

multiple choice question. extensive deposits of —— provide evidence that earths atmosphere began to contain oxygen released from photosynthesis beginning about 2 billion years ago. iron sulfur iridium carbon

Explanation:

When oxygen started being released by photosynthesis about 2 billion years ago, it reacted with iron in the Earth's crust and oceans to form iron - oxide deposits (rust). These extensive iron deposits are evidence of the presence of oxygen in the atmosphere. Sulfur, iridium, and carbon deposits are not directly related to the onset of oxygen - containing atmosphere from photosynthetic oxygen release.

Answer:

A. iron