Where did the oxygen in the water product come from

Oxygen can get into the water in several ways: Oxygen from the atmosphere dissolves and mixes into the water's surface. Algae and underwater grasses release oxygen during photosynthesis. Water flows into the Bay from streams, rivers and the ocean.

Explanation:

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

the earth would become to overheated and everything alive on it will eventually die from overheating. plants will eventually die as well, water will evaporate, and it will be nothing but a hot planet without anything living on it.