premise: photosynthesis is a source of oxygen sent2: early photosynthetic life is a kind of photosynthetic life sent3: earth had no / little oxygen a very long time ago sent4: the photosynthetic life performs photosynthesis sent5: early photosynthetic life existed a long time ago sent6: a source of something increases the amount of that something sent7: oxygen level describes an amount of oxygen.
hypothesis: 35 gram is the mass of that object