12. A monochromator had a focal length of 0.65 m was equipped with an echellette grating of 2000 blazes per millimeter. If 3.0 centimeter of the grating were illuminated, please calculate the reciprocal linear dispersion (in nm/mm)； resolving power, minimum difference of wavelength (in nm) can be resolved and slit width (in µm) of the instrument for the first order spectra at approximately 560 nm. Give the equations: (A) 0.77nm/mm, 6.0×104, 0.0093 nm, 6.0 µm.(B) 0.57 nm/mm, 6.0×104, 0.0063 nm, 12 µm.(C) 0.57 nm/mm, 7.2×104, 0.0093 nm, 6.0 µm.(D) 0.77 nm/mm, 7.2×104, 0.0063 nm, 6.0 µm.(E) 0.77 nm/mm, 6.0×104, 0.0093 nm, 12 µm