Pick up the correct statement from the following:
(A) It is difficult to eliminate an error completely at first trial
(B) Instability of the instrument makes it almost impossible to adjust it satisfactorily
(C) Adjustment screws must be left bearing firmly but should never be forced
(D) All the above
(A) It is difficult to eliminate an error completely at first trial
(B) Instability of the instrument makes it almost impossible to adjust it satisfactorily
(C) Adjustment screws must be left bearing firmly but should never be forced
(D) All the above