This might be wrong but I think it’s B
According to a source the answer is <span><u>Cyanobacteria were the first organisms to produce oxygen in water, which then escaped into the atmosphere.</u>
These cyanobacteria species were the first ones to "produce" oxygen as a by-product of the photosynthetic mechanisms which enables organisms to make their own food. </span>
Answer The species is known from three individuals, all of which were found in the Habib Rahi Rock Formation of Pakistan
Maiacetus is significant because of how well the skeletons were preserved. Over 90% of the bones from the male were found intact, which is almost unheard of for a specimen this old!
Their skeletons have all been found among fossils of sea-creatures which suggests they lived in the sea.
The fore-snout is starting to elongate. An elongated fore-snout is found in all modern whales and all transitional whales after Maiacetus.
