What type of irrigation method does this diagram represent?

• Contour ploughing or Contour Farming or Contour Bunding:
It is the farming practice of ploughing and/or planting across a slope following its elevation contour lines. So, option 3 is correct.
These contour lines create a water break which reduces the formation of rills and gullies during times of heavy water run-off; which is a major cause of soil erosion.
The water break also allows more time for the water to settle into the soil. 
In contour ploughing, the ruts made by the plough run perpendicular rather than parallel to slopes, generally resulting in furrows that curve around the land and are level.​

🔴Additional Information:
In free flooding, Ditches are excavated in the field either on the contour or up and down the slope. This method is suitable for close growing crops, pastures etc. This method is suitable on rolling land of irregular topography, where other methods are not suitable.
In Border flooding, the land is divided in to number of strips, separated by low levees called borders.
Check flooding is similar to ordinary flooding except that the water is controlled by surrounding the check area with low and flat levees. This method is suitable for more permeable soils as well as for less permeable soils.
In furrow flooding method, only one-fifth to one-half of the land surface is wetted by water. In this method, evaporation loss is very low.