Intensive cultivation refers to option 3, which involves raising production by intensive use of existing land. This means maximizing productivity on a given plot of land by using various techniques such as crop rotation, multiple cropping, and advanced irrigation methods. This option does not involve increasing labor or fertilizer inputs, nor does it rely on importing large quantities of inputs. Instead, it focuses on maximizing the output of a specific area of land through strategic and efficient use of resources. This approach is often used when there is limited available land and a need to increase agricultural production to meet the growing demand for food.