Light of wavelength $\lambda$ is incident on a diffraction grating with slit spacing $d$. A set of lines is seen on a screen. What angle $\alpha$ is formed between the two first order lines?
- A$\sin^{-1}\!\left(\frac{\lambda}{2d}\right)$
- B$\sin^{-1}\!\left(\frac{\lambda}{d}\right)$
- C$2\sin^{-1}\!\left(\frac{\lambda}{2d}\right)$
- D$2\sin^{-1}\!\left(\frac{\lambda}{d}\right)$