उत्तर : 4. "ऑलिपस मेसी"
व्याख्या :

Olympus Mons, first identified by Nasa's Mariner 9 spacecraft in 1971, is a shield volcano towering at a height of 21.9 km, making it two and a half times taller than Mount Everest. It is the largest volcano in the entire Solar System.