What process formed the oceans on Earth?

The formation of the oceans on Earth primarily involved water vapor condensing as the planet cooled. In the early stages of Earth's development, the planet was extremely hot and volcanic activity released a significant amount of water vapor into the atmosphere. As Earth gradually cooled, this water vapor began to condense and fall as rain, filling low-lying areas and forming oceans.

This process explains why the oceans contain a large amount of the Earth's water today. The other processes listed do not address the initial formation of oceans as directly. Melting of ice caps, rivers flowing into basin areas, and ice from comets melting might contribute to water levels or the distribution of water but are not the primary mechanisms by which Earth's oceans were formed in the geological past.