. . . . . . . . is an extensive method of vegetable cultivation.

Answer: Option B

Truck gardening is an extensive method of vegetable cultivation.
Truck gardening is the method of growing special vegetable crops in relatively larger quantities for distant markets by employing extensive methods. In this method of gardening, in general, a more extensive and less intensive method of cultivation than market gardening is followed.
Such farms are located far away from the centre of consumption preferably by the side of rail routes or metallic roads, which makes it easy to be transported.