Why does mars have one of the largest volcanoes in the solar system?

Sequoia national park  /  inyo national forest, california, u.s. mount whitney is the tallest mountain in california, as well as the highest summit in the contiguous united states and thesierra nevada—with an elevation of 14,505 feet (4,421 m).

Answertaurus is the highest in the sky;

Lol why dont you actually do the work instead of have people do it for you. jk i do it too lol