The areas under Ryotwari Settlements were surveyed after how many years?

30 years

The correct answer is Option (3) → 30 years

The Ryotwari Settlement:

The revenue system that was introduced in the Bombay Deccan came to be known as the ryotwari settlement. Unlike the Bengal system, the revenue was directly settled with the ryot. The average income from different types of soil was estimated, the revenue-paying capacity of the ryot was assessed and a proportion of it fixed as the share of the state. The lands were resurveyed every 30 years and the revenue  rates increased. Therefore the revenue demand was no longer permanent.