Question

which of the following is the most precise device for measuring length
(a) a vernier callipers with 20 divisions on the sliding scale.
(b) a screw gauge of pitch 1 mm and 100 division on the circular scale.
(c) an optical instrument that can measure length within a wavelength of light ?​

Answer 1

(c) an optical instrument that can measure length within a wavelength of light

Answer 2

Answer:

a) is the answer... hope I am correct