Prior to the development of photosynthesis, which of the following types of metabolism were common and which were rare or non-existent? Explain why.
1) Aerobic metabolism was common, while anaerobic metabolism was rare or non-existent.
2) Anaerobic metabolism was common, while aerobic metabolism was rare or non-existent.
3) Both aerobic and anaerobic metabolism were common.
4) Both aerobic and anaerobic metabolism were rare or non-existent.