A green light beam with wavelength $550\ \text{nm}$ falls normally on a diffraction grating and forms a diffraction pattern on a screen that is $3.5\ \text{m}$ away from the diffraction grating. The third-order maximum on the screen is $0.75\ \text{m}$ from the zeroth-order (central) maximum. Calculate the spacing between two neighbouring slits in the diffraction grating.
- A$2.6 \times 10^{-6}\ \text{m}$
- B$7.7 \times 10^{-6}\ \text{m}$
- C$7.9 \times 10^{-6}\ \text{m}$
- D$1.0 \times 10^{-5}\ \text{m}$