Fraunhofer diffraction pattern of a parallel beam of light (wavelength λ) passing through a narrow slit (width a) is observed on a screen using a convex lens (focal length f). The angular half-width of the central fringe is
(A) \(\cfrac{2λf}a\)
(B) \(\cfrac{λf}a\)
(C) \(\cfrac{2λ}a\)
(D) \(\cfrac{λ}a\)
