Coherent light consisting of two wavelengths ${\lambda }_1$ = 4500$\stackrel{0}{A}$ and ${\lambda }_2$ = 6000$\stackrel{0}{A}$ is sent through both slits of a Young's double slit apparatus:

 The third order bright fringe of ${\lambda }_2$ will coincide with fourth order bright fringe of ${\lambda }_1$

The third order bright fringe of ${\lambda }_1$ will coincide with the fourth order bright fringe of ${\lambda }_2$

The fringes of wavelength ${\lambda }_1$will be wider than the fringes of wavelength  ${\lambda }_2$

Central maxima for both wavelengths will coincide