Concept:Farm survey equipment are tools used for measuring land, distances, angles, and elevations during farm survey.Explanation:Cross staff is an equipment used to set out right angles on the farm.Abney level is an equipment used for measuring slopes and angles.Chain is also a standard equipment used for measuring distances in farm survey.Datun is not a known farm survey equipment or instrument.Therefore, the option that is not a farm survey equipment is datun.Answer:C. datun