According to the provided reference, Mercury has the greatest percentage of oxygen in its atmosphere.
It's crucial to distinguish between percentage and absolute quantity. While Mercury has a higher percentage of oxygen in its atmosphere compared to other planets listed in the reference, its atmosphere is incredibly thin. This means the total amount of oxygen is likely very small.
A more accurate answer, considering the total amount of oxygen, would be Earth. Earth's atmosphere is approximately 21% oxygen, and it has a significantly thicker atmosphere than Mercury. Therefore, Earth contains vastly more oxygen in total.
Therefore, based on the prompt's wording and the provided reference, the answer is Mercury due to the highest percentage. However, keep in mind that if the question asks about the total amount, the answer is Earth.
