Here's why:

* El Capitan: Located in Yosemite National Park, El Capitan is a granite cliff face towering over 3,000 feet (914 meters) high. It's considered the largest granite monolith in the world.

* Dome: While "dome" can refer to a geological formation, it's not a specific rock like El Capitan.

* Stone: "Stone" is a general term and doesn't refer to a specific large rock formation.

Therefore, El Capitan is the largest monolithic rock amongst the options you provided.