Final answer:
Earth uniquely possesses liquid surface oceans at the current time, while mountains, clouds, polar ice caps, and valleys can be found on other planets as well. Freshwater is primarily stored in Earth's glaciers and ice caps.
Step-by-step explanation:
Earth is unique in having several features, but when considering what is unique at the present time, surface oceans (A) are a defining characteristic. No other planet in our solar system currently has liquid surface oceans. On Earth, oceans cover about 71% of the planet's surface and are a central component of the global climate system, support a vast biodiversity, and are crucial for human life and the functioning of the biosphere. Mountains, atmospheric clouds, polar ice caps, and valleys are also features of Earth, yet they are not unique to our planet when considering other bodies in the solar system. For example, Mars has a seasonal polar ice cap made of water ice and carbon dioxide ice. The red planet also has evidence of valleys and atmospheric clouds, including water-ice clouds that form around mountains, much like on Earth.
The majority of Earth's freshwater is contained in glaciers and ice caps (E), representing a significant reservoir that impacts global sea levels and the availability of freshwater for ecosystems and human use. During Earth's geological history, particularly in periods such as the 20th century (d), global warming has led to the melting of polar ice caps and glaciers, contributing to rising sea levels and changing freshwater storage.