The difference of level between a point below the plane of sight and one above, is the sum of two staff readings and an error would be produced equal to

[A].	the distance between the zero of gradient and the foot of the staff
[B].	twice the distance between the zero of graduation and the foot of the staff
[C].	thrice the distance between the zero of graduation and the foot of the staff
[D].	none of the above.

Answer: Option B

Explanation:

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