B. The carrying out on agricultural land comprised in an agricultural unit of not less than 0.4 but less than 5 hectares in area of development consisting of—
(a)the extension or alteration of an agricultural building;
(b)the installation of additional or replacement plant or machinery;
(c)the provision, rearrangement or replacement of a sewer, main, pipe, cable or other apparatus;
(d)the provision, rearrangement or replacement of a private way;
(e)the provision of a hard surface;
(f)the deposit of waste; or
(g)the carrying out of any of the following operations in connection with fish farming, namely, repairing ponds and raceways; the installation of grading machinery, aeration equipment or flow meters and any associated channel; the dredging of ponds; and the replacement of tanks and nets,
where the development is reasonably necessary for the purposes of agriculture within the unit.