Subirrigation requires

a. an underground water source

b. a system of overhead sprinklers

c. a large flat area of land

d. a small amount of wind

Correct A.) An underground water source

The sub-irrigation is the method of watering plants from the below instead of above the ground. It is also known as seepage irrigation. In this method of irrigation water is sprayed directly to the plant root zone directly and it is directly taken up by the roots to the plants. It is an environmentally responsible alternative method that conserves water and fertilizers.

Hence, the correct answer would be option A.

the  frequency of a wave represents  the number of wavelengths that pass a specific point per second. the unit for  frequency  is hertz (hz).

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you must remain stopped until the stop signal is retracted and the red lights are turned off. approaching traffic in the opposite roadway of a divided highway shall not be required to stop, even if the school bus has the stop-arm extended and the alternately flashing warning signal lamps on.