Question

Choose the correct answers from the alternatives given .
Which of the following statements is true?

• A. It took so long for prokaryote evolution because the primitive atmosphere screened out the ultraviolet radiation from the Sun
• B. Primitive atmosphere was an oxidising one and todays is a reducing one, making photosynthesis possible
• C. Reducing primitive atmosphere contributed to the origin of life, and the oxidising one of today would hinder it
• D. Primitive atmosphere contains 20% oxygen, just like it is today

Answer 1

The correct option is C Reducing primitive atmosphere contributed to the origin of life, and the oxidising one of today would hinder it

The early atmosphere of earth was made of nitrogen and carbon dioxide gases before life began. When the photosynthesizing organisms multiplied then the carbon dioxide was replaced by oxygen. So, the correct option is "reducing primitive atmosphere contributed to the origin of life, and the oxidizing one of today would hinder it".