Since all the meter scales have same marking or scaling, thus it is not possible to have a defect in labelling of scale. Also the material of scale can't effect the labellind and thus measurement.
also, as the desk length is a linear measurement which does not involve any angular point, thus student can't read from differnet angles.
Hence, the most likely reason for the difference in measurement is:
A. One student read the meter stick incorrectly
