The accuracy of an Electronic Distance Measuring Instrument

M: +1.00/-0.33

The accuracy of an Electronic Distance Measuring Instrument (EDMI) is specified as
. Which one of the following statements is correct?

[GATE CE 2017 Set 1]

A Both a and b remain constant, irrespective of the distance being measured.

B a remains constant and b varies in proportion to the distance being measured.

C a varies in proportion to the distance being measured and b remains constant.

D Both a and b vary in proportion to the distance being measured.