Pick up the correct statement from the following:
(A) An observation or the resulting reading with the level on a levelling staff is called sight
(B) A back sight is the first sight taken after setting up the instrument in any position
(C) The first sight on each change point is a fore sight
(D) All the above
(A) An observation or the resulting reading with the level on a levelling staff is called sight
(B) A back sight is the first sight taken after setting up the instrument in any position
(C) The first sight on each change point is a fore sight
(D) All the above