Photosynthesis and cellular respiration are both complementary and relatively balanced on modern Earth, but early history of life on Earth showed increasing oxygen concentrations 2.5-2 billion years ago. This indicates that

d. the amount of photosynthesis occurring exceeded the amount of cellular respiration.

Explanation:

In the process of photosynthesis, oxygen is produced from carbon dioxide as plants make their own food. In cellular respiration, carbon dioxide is formed as oxygen is used to covert sugar into energy.

Photosynthesis produces oxygen and respiration produces carbon dioxide. If oxygen concentrations are increasing therefore, it means that more oxygen is being produced than being used which means that the amount of photosynthesis occurring must be higher than respiration because it is producing more oxygen than respiration can use.