The correct answer is - D. volcanic eruptions.
In recent studies and research about the water on our planet and how it came to be, the scientists managed to find new evidence that suggest that not only the comets and asteroids contributed to the existence of water on our planet, but also the volcanoes.
The volcanoes are actually releasing into the atmosphere the material from the deeper part of the Earth, the mantle layer. The mantle layer, as it turns out, has water in its rocks, so through the volcanic eruptions, that were much more and much bigger in the distant past, that water got released into the atmosphere. From the atmosphere, that water was falling on the surface, thus contributing to the creation of the first oceans on Earth.
