The most important agricultural product of Iran (a)   .

The traditional structure for transferring underground water in Iran is called (a)   .

Agriculture that is only dependent on rainfall is called (a)   .

Drip irrigation (a)   helps to consume less water.

One of the main problems in agriculture in Iran is (a)   water.

To prevent soil erosion, one should use (a)   (e.g., planting cover crops or trees).