Question

a piece of land that extends outward from a continent and is surrounded by water on three sides
choose
mountains
plateau
plain
valley
peninsula
at connects two large landmasses
ily surrounded by land

Explanation:

A peninsula is defined as a landform that extends from a continent and is surrounded by water on three sides. Mountains are large landforms that rise prominently above their surroundings. A plateau is an elevated flat - topped area. A plain is a flat, relatively low - lying area. A valley is a low area between hills or mountains. Since the description in the question matches the definition of a peninsula.

Answer:

Peninsula