When used for alignment, a dumpy level is accurate at distances up to how many feet?

A dumpy level, also known as a survey level or optical level, is designed for surveying and construction tasks that require accurate leveling and alignment over distances. The typical range for reliable accuracy when using a dumpy level is up to about 1,000 feet. This distance ensures that the instrument can provide precise readings without being adversely affected by the curvature of the Earth or atmospheric conditions that can distort measurements over greater distances.

At distances beyond 1,000 feet, factors such as the Earth's curvature, changes in elevation, and potential obstacles can introduce errors, making measurements less reliable. Therefore, the 1,000 feet limit reflects standard practices in surveying, where maintaining accuracy is essential for successful project outcomes. This makes it clear why this choice stands out as the correct answer.